rear bump stops

[vxfocus]

anybody ever replace your rear bump stops with the energy suspension part number 9.9104r?
the stock bump stops are two bolt mounting and the e.s. stops are one bolt in the middle.
just wondered what was involved in making the switch.
thanx

[Ldub]

6th & 7th pic from the top...:_wrench:

http://www.vehicross.info/forums/showthread.php?t=13415&highlight=big+beast

[ZEUS]

Didn't look the part number you posted but I am guessing you mean this:
http://www.vehicross.info/gallery/data/500/Bumpstop.JPG

After a few hits over a couple years the metal plate started to deform a bit causing a crack in the poly - using a 1x3 steel tube spacer rather than the OEM bump stop backing piece would work better long term. They work great with oversize tires but big offset mixed with big tires need more of a spacer to keep the tire off the cladding when flexing.

[ZEUS]

6th & 7th pic from the top...:_wrench:

Amateur and traitor! :p

[vxfocus]

6th & 7th pic from the top...:_wrench:

http://www.vehicross.info/forums/showthread.php?t=13415&highlight=big+beast

thanx ldub,,thats what i needed

[Ldub]

Amateur and traitor! :p

Meh...:_confused

It was closer to the top of the list when I searched, so you can add lazy too...:laughing:

[blacksambo]

Remember, these are technically not bump stops but actually spring helpers and are there to help control roll resistance not suspension travel, per se. Just an FYI.

[Ldub]

Remember, these are technically not bump stops but actually spring helpers and are there to help control roll resistance not suspension travel, per se. Just an FYI.

With that in mind, the bumps should in theory, be extended the same amount as the lift?

[Gizmo42]

I had to extend mine on the rodeo so my wider tires and wheels didnt rub.

http://img360.imageshack.us/img360/7751/0405081235in2.jpg

Cant say it does much for handling considering the weird handling I have now after snapping my rear sway bar on 7 mile rim this year.

[Ldub]

Cant say it does much for handling considering the weird handling I have now after snapping my rear sway bar on 7 mile rim this year.

That can be repaired with JB weld & carbon fiber duct tape...:yesgray:.:rotate:.:laughing:

[Gizmo42]

LOL. Still havent decided if I'm going to replace it. Handles a little weird but not horrible. The back end tries to roll while the front stays flat-ish.

[VXorado]

LOL. Still havent decided if I'm going to replace it. Handles a little weird but not horrible. The back end tries to roll while the front stays flat-ish.

I'm going through the same thing with the front sway bar. My sway bar links were shot and making alot of noise over bumps so I removed the bar to source replacement links. Now I've been driving around without it for a few weeks and its fine. Theres a little more body roll without the sway bar but the VX rides over bumps much smoother.

[tom4bren]

There's a high rise 4-Runner in my neighborhood that has his sway bars removed. I swear that his side mirrors scrape the pavement when he corners.

[vxfocus]

ok got the bump stops on.since i dont have a lift and was just replacing the original stops i wanted to keep as close to original height as i could.the e.s. ones are a little bit longer.
so i just took the old ones off and drilled a single hole in the factory mount location and with a bit of messing around with holding the nut with a wrench in side the channel i got em on.
http://i405.photobucket.com/albums/pp139/kenhalford/1312665250.jpg
http://i405.photobucket.com/albums/pp139/kenhalford/1312665248.jpg
they sit right on the rear axle.does that mean my springs are too weak?my original stops where all tore up.if so anyone know anywhere i can get new springs?

[VX KAT]

Many many VXers found the stock rear bump stops were within 1/2" of the axle, and thus, the extremely slamming/jarring effect in the rear when we hit bumps. Some, like me, chose to cut the rears in half to gain more distance. Dramatically improved, the ride, along with the Rancho 9000XLS shocks.

[Gizmo42]

Try them and see how it rides. Looks like they might be collapsible like the ones on my rodeo. Mine sit about 1" off the axle but I dont feel it until it fully collapses.

[LittleBeast]

ok got the bump stops on.since i dont have a lift and was just replacing the original stops i wanted to keep as close to original height as i could.the e.s. ones are a little bit longer.
so i just took the old ones off and drilled a single hole in the factory mount location and with a bit of messing around with holding the nut with a wrench in side the channel i got em on.
they sit right on the rear axle.does that mean my springs are too weak?my original stops where all tore up.if so anyone know anywhere i can get new springs?

Nah. I would roll with what you have going on there until you really plan on making a lot of changes. Looks great for now. If you want to add larger tires, lift, etc, then I would worry about stiffer taller springs, but until then, good job :-)

[vxfocus]

ok after a couple days of driving i need a kidney replacement!wow it rides rough,like it has a fixed axle with the bump stops resting right on the axle it doesnt let the coil springs do there job.
so i need some input from anyone who is running the ome 913s on what the ride quality is compared to the stock springs...its gotta be better than what i have now.
i was also thinking about the Set of Daystar Spring Spacers to give me about an inch and a half lift to get the stops of the axles
http://www.vehicross.info/gallery/data/3223/medium/Spacers_1sm.jpg

[vt_maverick]

I cut my stops and added the Daystar spacers after installing 265/60/18's on 8" wide, -2mm offset rims. Those spacers are like $35-40 shipped, if I were you I would order a set and try them out first - they may very well be all you need.

Low risk, big reward IMHO.

[yellowgizmo99]

I did just the spacers and it made a big difference and was easy to do, since it was the second time I had done it.

[vt_maverick]

I did just the spacers and it made a big difference and was easy to do, since it was the second time I had did it.

:) Thanks again Billy. :thumbup:

[vxfocus]

WOW!!ordered the spacers from summit yesterday and got them today!!
and another WOW!! because what a difference in the ride after i installed the spacers.i used the stock spring seats inside the spacers but not sure if i will leave them in or take them out it sits a little high in the back with stock 16s it might be a little much.
here is a pic to show how much lift the spacers give keep in mind that before i installed them the bump stops were sitting on the axle.
pic is kinda dark..flashlight and cell phone lol but you get the idea
http://i405.photobucket.com/albums/pp139/kenhalford/1313025850.jpg

[RickOKC]

I suspect your springs may be worn out. :(

The official "before" measurements on mine were: 1/4" gap between bump stop & axle on the right and the left side was resting on the axle. I bought a pair of used springs and new insulators and now I have 1/2" both sides. Rides smoother and corners better. :) Even if you keep the spacers, I wonder if you would get the same benefits with fresh springs, too. :_confused

[vxfocus]

i did think about spring replacement but the bump stops i put on were longer than the stock ones so replacing the spring might not have lifted them off the axle enuff.so i went with the 40 dollar option.

[xdfarrx]

Does someone have a part number or link to Summit for the spacer kit. Ive inferred its a reasonable mod for stock wheel size [I have aftermarket wheels and tires but same fitment]. I had how mine jar.
Thanks much...
xdx

[eblank]

Does someone have a part number or link to Summit for the spacer kit. Ive inferred its a reasonable mod for stock wheel size [I have aftermarket wheels and tires but same fitment]. I had how mine jar.
Thanks much...
xdx

If you would like a used stock set of springs to mess with, I've got a set that are yours for the price of shipping. I'm moving this week and they will be thrown out otherwise. Let me know if you (or anyone else for that matter) wants them.

[xdfarrx]

Thank you but I have a stock set. Did all my sway linkages with the energy stuff years ago. Thought I would update my stops. Dont throw them away, pay it forward or sell them. Good luck with the move :)

[Maddawg]

Remember, these are technically not bump stops but actually spring helpers and are there to help control roll resistance not suspension travel, per se. Just an FYI.

I know this thread is pretty much dead, but for others coming in as of late, I would like to say that I disagree with you blacksambo.
Those are bump stops and they DO limit suspension travel. They may affect roll resistance but primarily that's what the sway bar does. I have removed my rear bump stops completely (not recommended unless you have a lift) it does not affect roll/sway on my VX at all, still handles like it always did, but without the harsh jarring of the bump stops.:p

[blacksambo]

I know this thread is pretty much dead, but for others coming in as of late, I would like to say that I disagree with you blacksambo.
Those are bump stops and they DO limit suspension travel. They may affect roll resistance but primarily that's what the sway bar does. I have removed my rear bump stops completely (not recommended unless you have a lift) it does not affect roll/sway on my VX at all, still handles like it always did, but without the harsh jarring of the bump stops.:p


I gotta tell ya....our two '99's handle with ease. NO jarring or anything untoward at all. These are after all sport trucks...what do people expect, 1978 Cadillacs?? The parts we are all talking about rides about one quarter of an inch above the axel plate, motionless. Once under way they are in constant contact with the axel. I think, to expect touring car ride in a fairly hi-performance, legacy SUV is expecting too much, perhaps. Let's let the original design do it's intended job. Saw if you must, but do so at your own safety peril.

[VX KAT]

I gotta tell ya....our two '99's handle with ease. NO jarring or anything untoward at all. These are after all sport trucks...what do people expect, 1978 Cadillacs?? The parts we are all talking about rides about one quarter of an inch above the axel plate, motionless. Once under way they are in constant contact with the axel. I think, to expect touring car ride in a fairly hi-performance, legacy SUV is expecting too much, perhaps. Let's let the original design do it's intended job. Saw if you must, but do so at your own safety peril.


Awe come on Sambo, you know none of us are thinking old Cadillac ride, not even close to that so don't go there. Many of us have or have had, other SUVS/trucks etc so we know how various types of trucks ride.
If your 2 VXs don't make a slamming/jarring/bang sound/jolting vibration of rather significance, when you go over larger highway seams, or on a rough dirt road, or a rough gravel road, with any type of rut or horizontal dip or rise of any kind...then.....um....um....you can't be driving a VX. :_thinking

Going only 22-25mph on my rough, rutted rocky dirt road causes my dash mounted compass, on a hinge, to jump/bobble up and down about 1/2"....and the hinge is secure, not loose. That's the slamming vertical lift I get from the rut or gully.

It also causes a very significant vibration in the steering wheel, significant sensations/vibrations and movement of the steering column.
Could it be that your normal travels just don't take you on roads of this type, and therefore, you don't experience it?

Just going by sheer statistics here, if say, 80% of forum members comment on a rough jarring/slamming/ride over rough horizontal surfaces, and only 2 say "I gotta tell ya....our two '99's handle with ease. NO jarring or anything untoward at all."......ya gotta admit, that's kind of odd, statistically speaking.

All the VX owners that have commented on the jarring ride have come from different model years, different locales, different terrain, different mileage, different ages, different condition of the vehicle...and yet they all describe the very same issue, in the same set of circumstances....that would seem to make it a valid issue IMHO.

Again, my only 2 thoughts I could come up with to explain this 2 vs. many many owners, is to theorize you to don't encounter the type of terrain that the others describe. .....and secondly, you just have a different perception/feeling of this event when it occurs? :_shrug:

Point is....perhaps your driving just doesn't put you in such circumstances...and therefore, you don't perceive it that often, or at all.

I legitimately can't think of any other possibilities for the stark difference of opinion.....

there's my 2 cents :thumbup:
p.s....I am not making any commentary about the function of the bump stops...what they are called or what their official function is....just discussing the slamming/jolt in the ride.

[blacksambo]

No quarell with your member statistics. My point is actual performance versus expectations. Our trucks are a fifteen plus year old design. Old SUV technology . I think VX's suffer from not looking old, but in fact are practically antiques. Expecting 21st century ride characteristics may not be realistic?

[Maddawg]

I have to totally agree with Sue. I understand that its a truck and won't feel or drive like my Izusu Axiom for example. But my real truck (stock Chevy) is able to negotiate nasty, bumpy, washboard roads with little or no impact on the coffee cup between my legs. Even though I account for the short wheel base of the VX and try to drive accordingly, its a 5 mile an hour (or less) creeping along drive. There is absolutely no doubt in my mind that this vehicle is either mis-engineered or intended for paved road use only.

[tom4bren]

... no impact on the coffee cup between my legs.

Darwin much???:):):)

[Maddawg]

Sorry Tom, that one's over my head. (Charles Darwin?)

[VX KAT]

Darwin much???:):):)


Sorry Tom, that one's over my head. (Charles Darwin?)

possibly about having hot coffee between youz boyz thighs...and decreasing chance for reproducing yungun's maybe? ya know Darwin's "survival of the fittest"...er, um, I mean dumbest....
Don't know if it's over our head or just under Tom's? :goof: :_confused....:slap:

[Maddawg]

Hahahahah, never would have got that without your help Kat! But I think its cold that hurts the little swimmers, not heat. Either way its not pleasant. :eek:

[Vendetta]

Nope, it's the heat. That's why they hang, man. "Ya gotta keep 'em separated!"

Also, easiest way for a dude to tell if he's running a fever is when they're like dragging on the floor.

And there's today's bio lesson. ;-)
-V

[tom4bren]

Y'all think too much.

Riding around in any car with a scalding hot beveridge in a flimsy cup in close proximity to such a sensitive manly organ is not a sign of being a mental giant.

Doing it in a vehicle with the bumpity ride quality of the VX ... that's just Darwin Award material right there.

:):):):)

There's the smilies for ya so you know I'm just rattlin yer cage. After all I'm the one that had to learn the hard way that you should never, ever, ever, never, ever hit a basketball with a baseball bat (KAT - hubby can tell you what the theoretical outcome would be).

But at least I'm NOT the one who tried to use my shoulder as a wheel chock.:)

[VX KAT]

Nope, it's the heat. That's why they hang, man. "Ya gotta keep 'em separated!"

Also, easiest way for a dude to tell if he's running a fever is when they're like dragging on the floor.

And there's today's bio lesson. ;-)
-V

Yup, it's the heat...that's mostly why I don't have any kids....first hubby had hardly any swimmers........oops, that might be TMI....:mbrasd:

[tom4bren]

How the heck did 2 different threads degenerate into the same conversation at the same time???

[VX KAT]

How the heck did 2 different threads degenerate into the same conversation at the same time???

it's what we do....:laugho:

[Maddawg]

Geeee, and all I said was.................lol. :) :)

[tom4bren]

There's the problem ....

:_brickwal

[RickOKC]

I needed a good laugh.

This conversation... just nuts.

[Vendetta]

I needed a good laugh.

This conversation... just nuts.

I see what you did there.

[workmeistr]

So...should I cut down my rear bump stops?;Do;

[PK]

So...should I cut down my rear bump stops?;Do;

Apparently you only do this modification -


















if you think it will help keep your nuts cool.:yeso::yesb::yesgray::p

PK

[SlowPro48]

So...should I cut down my rear bump stops?;Do;

They're not bump stops until you chop them in half. Until then they're spring helpers. :bgwb:

[workmeistr]

I now, then, have bump stops. Cut mine yesterday. I removed and cut on the bench. I really haven't noticed much of a difference, MTF.

[RickOKC]

Hey Bren, I haven't said "hi" for a long time so... "HI!" Do you still have the original shocks? Or replacement original shocks?

I met a local VXer recently and he let me crawl all over/under his VX and then he took me for a ride around the block. His VX rides quite a bit smoother than mine on the factory original shocks (and I have the softer Rancho XL9000s!) Our unmodified spring-helper-bump-stops-whatever seem to sit at the exact same position so.... I'm pondering on why they ride so differently. :_confused

Now I'm curious if brands of tires, inflation pressures & various minor differences between hand assembled vehicles may make a difference ranging from small to big.

(BTW, I think his local '99 Astral may be up for sale soon... I'll add more input if he posts it.)

[89Vette]

Hey Bren, I haven't said "hi" for a long time so... "HI!" Do you still have the original shocks? Or replacement original shocks?

I met a local VXer recently and he let me crawl all over/under his VX and then he took me for a ride around the block. His VX rides quite a bit smoother than mine on the factory original shocks (and I have the softer Rancho XL9000s!) Our unmodified spring-helper-bump-stops-whatever seem to sit at the exact same position so.... I'm pondering on why they ride so differently. :_confused

Now I'm curious if brands of tires, inflation pressures & various minor differences between hand assembled vehicles may make a difference ranging from small to big.

(BTW, I think his local '99 Astral may be up for sale soon... I'll add more input if he posts it.)

tire weight? oem inflation is 29lbs according to my local NTB.

use: city/hwy/off-road = less suspension wear

[RickOKC]

Hi 89Vette, long time, no talk. (And, BTW, thank you for all the questions you asked when we were both VX shopping at the same time. Your questions were so much better than mine and the responses you got helped me decide to buy a VX.)

So, what tires do you have?

I think there's a good probability that my ride quality has been reduced 'cuz I went with non-OEM tires and they are about 3" taller than stock. Funny, they actually improved and rode smoother in everyday driving once I boosted them up from OEM to about 40psi. To me it doesn't seem right that the higher pressure makes for a better ride. But.... I'm not a tire expert so there is obviously something I'm missing! :)s

[VXorado]

tire weight? oem inflation is 29lbs according to my local NTB.

use: city/hwy/off-road = less suspension wear


Should we be using 29lbs inflation with over-sized tires?

[89Vette]

Should we be using 29lbs inflation with over-sized tires?

Good question. You MIGHT even want to use less.

More seems to improve MPGs -- like you'd expect. Less probably gives the better ride. I've also run less with the vette. Figure it's better to enjoy the car and ride (loosing some tire life) than getting best mpg's possible.

I'm running 285/60-20's. Maybe a hair less sidewall height that OEM. They made the ride a bit harsher than the fluffy 285/70-16's that I bought it with.

With the former, 35psi felt about right and I got better mpg. 35psi is a bit too stiff now that I have shorter sidewalls. So really, that's probably the biggest indicator vs the overall size.

[89Vette]

Hi 89Vette, long time, no talk. (And, BTW, thank you for all the questions you asked when we were both VX shopping at the same time. Your questions were so much better than mine and the responses you got helped me decide to buy a VX.)

:thumbup:

How much sidewall do you have compared to before? By ride, are you referring to handling or cushy-ness.

[tom4bren]

I don't care what the techies say. I always have & I always will inflate my tires to the TIRE mfr recommended pressure rather than what is on the doorjam of the vehicle. Think about it. The VX is 10+ years old. Do you really think that Isuzu had a crystal ball back then to KNOW what innovations/improvements would be made to tire technology over the course of the next decade??? Look at all of the variety of tires out there: MT/AT/street, 6/8/10 ply, directional versus not, speed ratings, life ratings, temperature ratings. How can one recommended tire pressure work for all???

That said: it's just a starting point for me. I adjust the tire pressure to maximize life of the tire. Our MPG sux anyway so tire pressure really isn't gonna make that much of a difference. Maybe I'm a numb butt, but I really don't notice any difference in ride quality based on tire pressure anyway (especially with the VX ride quality - or lack thereof). With a 100 mile commute daily, it's all about making the expendables on a vehicle last as long as possible.

IMHO

That's my $.02 ... & I want change.:)

[pbkid]

Should we be using 29lbs inflation with over-sized tires?
You definitely want to run yours high pressure unless offroad Jon. You have so much sidewall, it would be dangerous to run yours low pressure at highway speeds.

Im with tom on this one, (wow thats hard to say) the tire pressure on the door jam is designed for the factory tires and doesn't compensate for mods or new tire technologies. I know it sounds nuts, but i run my tires at 55psi, and get 3-4 more mpgs out of em and ride quality is all in the shocks and springs. If your VX rides that bad I'd look into the heavy duty torsion bars.


I don't care what the techies say. I alwmodsays have & I always will inflate my tires to the TIRE mfr recommended pressure rather than what is on the doorjam of the vehicle. Think about it. The VX is 10+ years old. Do you really think that Isuzu had a crystal ball back then to KNOW what innovations/improvements would be made to tire technology over the course of the next decade??? Look at all of the variety of tires out there: MT/AT/street, 6/8/10 ply, directional versus not, speed ratings, life ratings, temperature ratings. How can one recommended tire pressure work for all???

That said: it's just a starting point for me. I adjust the tire pressure to maximize life of the tire. Our MPG sux anyway so tire pressure really isn't gonna make that much of a difference. Maybe I'm a numb butt, but I really don't notice any difference in ride quality based on tire pressure anyway (especially with the VX ride quality - or lack thereof). With a 100 mile commute daily, it's all about making the expendables on a vehicle last as long as possible.

IMHO

That's my $.02 ... & I want change.:)

[Ldub]

I don't care what the techies say. I always have & I always will inflate my tires to the TIRE mfr recommended pressure rather than what is on the doorjam of the vehicle.

I'm gonna have to disagree witcha Bro, & here's my take on it...yeh, I know...:rolleyesg

The pressure on the sidewall is not recommended pressure, it's the MAX that the tire is designed to handle, also, if you go read your sidewall, there is a max load associated with the max psi. Keep in mind that max load rating is per tire, so that #, x 4 is the total that all 4 tires are capable of carrying.

Tires with a higher volume (more width & sidewall height) require less pressure to achieve the same contact patch (correct inflation pressure for the load carried) than a tire with less volume.

Think of this comparison...

A racing bicycle tire, with very little volume, may require around 100 psi to carry a load that's 200 lbs or less...a 44x66 tire on an average monster truck, carries a total load (divided by four) of 10-12,000 lbs, & is typically inflated to 15 psi.

I'm not say'n that high psi is bad or dangerous, as long as you are satisfied with the wear etc, go for it.
It's the misconception of the max press on the sidewall being mistaken for a recommendation that I disagree with...:flower:

[tom4bren]

Im with tom on this one, (wow thats hard to say) ...

OUCH!!!


I'm gonna have to disagree witcha Bro, & here's my take on it...yeh, I know...:rolleyesg

The pressure on the sidewall is not recommended pressure, it's the MAX that the tire is designed to handle, also, if you go read your sidewall, there is a max load associated with the max psi. Keep in mind that max load rating is per tire, so that #, x 4 is the total that all 4 tires are capable of carrying.

Tires with a higher volume (more width & sidewall height) require less pressure to achieve the same contact patch (correct inflation pressure for the load carried) than a tire with less volume.

Think of this comparison...

A racing bicycle tire, with very little volume, may require around 100 psi to carry a load that's 200 lbs or less...a 44x66 tire on an average monster truck, carries a total load (divided by four) of 10-12,000 lbs, & is typically inflated to 15 psi.

I'm not say'n that high psi is bad or dangerous, as long as you are satisfied with the wear etc, go for it.
It's the misconception of the max press on the sidewall being mistaken for a recommendation that I disagree with...:flower:

I DO have a response to that ... actually 2.

1. PV=mRT

2. Watcha gonna do when the recommended pressure on the door jam is higher than the max pressure listed stamped on the tire???

:whiteflag:

[pbkid]

Aww cmon tom, like my dad always says, 'if im not razzin ya, that probably means i dont like you anymore'

[tom4bren]

Aww cmon tom, like my dad always says, 'if im not razzin ya, that probably means i dont like you anymore'

I think I told you once that you strike a disturbing resemblance to my nephew. If'n we're in fact fambly then ... GAME ON Peanut Butter!!!:)

[Ldub]

I DO have a response to that ... actually 2.

1. PV=eRT

2. Watcha gonna do when the recommended pressure on the door jam is higher than the max pressure listed stamped on the tire???

:whiteflag:

In response to:

1. . :confused:...P-vert?

2. . When that happens, lemme know, we'll talk...:yesgray:

[tom4bren]

Mt Dew tru da nose on dat 1 Mr. Dub:)

[SlowPro48]

I'm not say'n that high psi is bad or dangerous, as long as you are satisfied with the wear etc, go for it.
It's the misconception of the max press on the sidewall being mistaken for a recommendation that I disagree with...:flower:


Well I'll say it then. It's dangerous!

Example: max recommended pressure on my TerraGrapplers is 50psi. At that pressure there would be about 42% less rubber in contact with the road than what Isuzu intended, which will significantly increase stopping distance - and reduce lateral grip as well. Unless you're hauling a lot of weight, for safety's sake you might want to air down a little! Who knows - it might keep you from rear-ending somebody on the freeway someday. :razzgray: And BTW, 29psi is specified as cold - so pressure increase according to the Ideal Gas Law is already accounted for.

[RickOKC]

:thumbup:

How much sidewall do you have compared to before? By ride, are you referring to handling or cushy-ness.

I went with a tire that was 3" taller overall so there was a bit of growth. :) I'm talking strictly about ride comfort quality - I really haven't seen any noticible difference in handling except for when I had them aired down super low (15-20psi) for off-road. Some of the streets around here are in extremely poor condition!

[pbkid]

Well I'll say it then. It's dangerous!

Example: max recommended pressure on my TerraGrapplers is 50psi. At that pressure there would be about 42% less rubber in contact with the road than what Isuzu intended, which will significantly increase stopping distance - and reduce lateral grip as well. Unless you're hauling a lot of weight, for safety's sake you might want to air down a little! Who knows - it might keep you from rear-ending somebody on the freeway someday. :razzgray: And BTW, 29psi is specified as cold - so pressure increase according to the Ideal Gas Law is already accounted for.

I'm gonna agree to disagree with this statement. sure at rolling speed, you lose an amount of rubber contact with the road as the tires expand in the middle of the tread, but what happens when you press those brakes hard and the weight of the vehicle is thrown onto the front tires? you then have 100% contact and have regular tire grip.
Lets see if i can word this to make sense as it does in my head ;)
As well, if we are talking safety, which is my point for inflating my tires so high; if you have your tires at lower pressure, say 29 psi as your door jam suggests, how is your vehicle supposed to handle in a panic skid or quick swerve? My reasoning is, as your sidewall gives, it causes body roll, increasing chance of a rollover. I personally would rather skid a little (key word little), than have the tires grab hard and roll me over.
Now, this also supports my thought behind hard straight line braking, if you swerve and put the weight of the vehicle on 2 tires, you now are operating at optimal traction levels (enough to skid but also handle). Rather, at low tire pressure you increase your traction to a level of rollover or poor handling (low tire pressure proves to make for sloppy handling).

Let the bashing and arguments begin :smack: :slap: :smack: :slap:

[PK]

Wheres RiffRaff when ya need him??

He will sort you guys out.:yesy::yeso::p

PK

[tom4bren]

Well I'll say it then. It's dangerous!

Example: max recommended pressure on my TerraGrapplers is 50psi. At that pressure there would be about 42% less rubber in contact with the road than what Isuzu intended, which will significantly increase stopping distance - and reduce lateral grip as well. Unless you're hauling a lot of weight, for safety's sake you might want to air down a little! Who knows - it might keep you from rear-ending somebody on the freeway someday. :razzgray: And BTW, 29psi is specified as cold - so pressure increase according to the Ideal Gas Law is already accounted for.


I'm gonna agree to disagree with this statement. sure at rolling speed, you lose an amount of rubber contact with the road as the tires expand in the middle of the tread, but what happens when you press those brakes hard and the weight of the vehicle is thrown onto the front tires? you then have 100% contact and have regular tire grip.
Lets see if i can word this to make sense as it does in my head ;)
As well, if we are talking safety, which is my point for inflating my tires so high; if you have your tires at lower pressure, say 29 psi as your door jam suggests, how is your vehicle supposed to handle in a panic skid or quick swerve? My reasoning is, as your sidewall gives, it causes body roll, increasing chance of a rollover. I personally would rather skid a little (key word little), than have the tires grab hard and roll me over.
Now, this also supports my thought behind hard straight line braking, if you swerve and put the weight of the vehicle on 2 tires, you now are operating at optimal traction levels (enough to skid but also handle). Rather, at low tire pressure you increase your traction to a level of rollover or poor handling (low tire pressure proves to make for sloppy handling).

Let the bashing and arguments begin :smack: :slap: :smack: :slap:

I'm going to agree to disagree with both Y'all.

Traction is more a factor of tire design than it is air pressure. I know that my old Wrangler MTs had a stiff sidewall so tire pressure made very little difference on any of the factors you're talking about. The Firestone ATs I'm running now have a softer sidewall so I've got to keep a closer eye on the pressure - but only in terms of wear, handling seems unaffected. IIRC Marlin is running tires with Kevlar in the sidewalls. He can prolly run at 0 psi & not notice (yes, I'm exagerating).

[Cobrajet]

Let's compromise...

Tire pressure is a compromise. Optimum tire pressure is based on a multitude of factors. Tire design, tire size, temperature, vehicle weight, road conditions, etc. Take NASCAR for instance. During the course of a race the crew chief is constantly adjusting tire pressures to compensate for track conditions, weather/air temp, chassis adjustments, etc. Do they look at the pressure stamped on the side of the tire? Do they use a set pressure from the chassis maker? No. My tire pressures are based on my own experience and have little to do with whatever Tom or PK or SlowPro run their tires at. They don't have the same tires and wheels, so they run a different tire pressure. I personally don't think either the car mfg tire pressure on the door OR the max pressure on the tire sidewall is optimum. It's going to be somewhere in between. At least for me!

[evillecutter]

my tires say 55 psi my vx says 29 psi so i go 40psi and they both seem happy - the ride feels exactly the same as if they were 29 psi

[PK]

Let's compromise...

Tire pressure is a compromise. Optimum tire pressure is based on a multitude of factors. Tire design, tire size, temperature, vehicle weight, road conditions, etc. Take NASCAR for instance. During the course of a race the crew chief is constantly adjusting tire pressures to compensate for track conditions, weather/air temp, chassis adjustments, etc. Do they look at the pressure stamped on the side of the tire? Do they use a set pressure from the chassis maker? No. My tire pressures are based on my own experience and have little to do with whatever Tom or PK or SlowPro run their tires at. They don't have the same tires and wheels, so they run a different tire pressure. I personally don't think either the car mfg tire pressure on the door OR the max pressure on the tire sidewall is optimum. It's going to be somewhere in between. At least for me!

I fully agree with Cobrajet on this..
The optimum tyre pressure is very much a seat of the pants selection.
Just do not exceed the maximum stated on the tyre, as that is a safety requirement.
I run mine at 32PSI unloaded, and bump the rears to 36 if I have a heavy load in the back.
If you really want to get the optimum balance of good fuel consumption, and maximum tyre life, then use the chalk mark across the tyre method to match your tyre pressures to the load of the VX.

PK

[Triathlete]

I run my tires at 110psi on my daily driver :)

[89Vette]

Couple things:

Contact patch varies from tire to tire...And that can be with the same pressure. Changing pressure to stay in line with tire manufacturer's intended contact patch really is the correct solution. Thought there are other considerations... Bounce of the tire is matched with suspension travel, rebound rates, springs, etc... The suspension is geared up as a "unit" with the tires mounted from the factory. SUVs have a much bigger variance in tire selection/type than sedan (cars), so more has to be judged by the driver and performance. In general, though, I agree that starting with recommended manufacturer (VX suggested) pressure is your best option. My 285-50's will take way more pressure than 29psi. Even the stock, original tires would take more than 29psi. That should be your clue!

I think there's a ride trade-off vs. MPG. More air is gonna give better mileage by reducing the contact patch (that may or may not be starting at the same area as stock.) Here, it's only a matter of less patch=less friction. That will provide better MPG. But you'll have to judge issues with tire bounce and handling if you stray more than say....10-20%. No one can determine YOUR preference. Softer (until dangerously soft -- less than 20psi for example) should always make the ride softer -- as it will absorb more bumps.

I can't see how 20, or even 29psi, can feel the same as 40psi. There's gonna be some difference. The harder you drive, the more obvious it'll be.

Softer will "roll" more in turns and degrade handling. Harder may degrade traction -- especially in rain/snow.

Pick what's best for your taste, climate, and mpg/longevity concern. Really, there IS a correct pressure that determined by viewing tire wear and contact patch. So, you could/should let those decide for you. If you'be strayed too far from stock configuration, you may just have to compensate and adjust your suspension.

[Maddawg]

I run my tires at 110psi on my daily driver :)

What the hell is it a big rig 18 wheeler????????? :confused:

[TheGanzman]

I run my tires at 110psi on my daily driver :)

Is that ALL?! I'm running a buck-twenty!:bwgy: Looks like you and I are the only ones "in on" this one...;)

http://images.lilypix.com/albums/userpics/10077/normal_GanzBike2.JPG