cupping tires.. those running 285s

ive got about 6k on my new Falken STZ 04 in 285/60/18s and have noticed some cupping on both the inner and outer edges of the front tires.. i had them re-balanced and moved to the rear, but it seems like the ones from the rear that are now on the front are doing the same thing

I had my alignment checked three times since may... the most recent time the toe angles were dead on, the left side was dead on, but the right side is slightly out of spec for negative camber and right on the edge for caster

after speaking with Falken, they dont seem to think this is the problem, they are advising me to run the tires between 26-29 PSI (I was running them at 36) they also advised me that the rim is probably too small for the tire

i know many folks here have 285/60/18s on the factory wheels, are you noticing any uneven wear on them? what pressure do you run at?

I'm running 285/60/18 Nittos. I run my tires between 35 - 38 lbs. I have about 45 k on them, and wearing pretty even. I try to rotate mine every
5-7 k.
Peace.
Tom

Are you factory ride height? Alignments on lifts/lowers are a funny thing and I know to preserve your CVs you have to make a slight adjustment.

I ran super soft Yokohama AVSs on the factory rim for about a year sometime back and had no issues with inner wear. Probably had about 15k miles on them.

I did have the same issue on my WRX when I lowered it. Alignment would not help, even a performance alignment. It was concluded that the problem was the wheel offset, which was the same as stock (same size wheel/tire, just aftermarket). Going from a 52+ to a 44+ solved it.

Very strange....

I'd always heard that cupping was caused by bad shocks.

As far as offset is concerned ... mine have never shown any cupping but with MTs, it may be hard to tell. My fronts are VERY worn (but evenly) while the backs are still good - rekin I shoulda rotated more often but by the time I noticed it, it was too late.

Quote:

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Originally Posted by tom4bren

I'd always heard that cupping was caused by bad shocks.

As far as offset is concerned ... mine have never shown any cupping but with MTs, it may be hard to tell. My fronts are VERY worn (but evenly) while the backs are still good - rekin I shoulda rotated more often but by the time I noticed it, it was too late.

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:fyi:...you should always have your best tires on the steering axle, so blowouts, however unlikely, are more apt to happen on the rear axle.

nah im still factory height factory wheels
i think im gonna re-align it including shims for the caster/camber adjustments and see if that helps.. the shocks are new within the last 5k, so i dont think thats it

know this isn't much help, but thought I'd mention it......I had these same tires in 255/55-18, at 36 psi on OEM rims, for about 7k - 8k miles, (based on look of tread...they came with car....I only had them for about 2,500 miles) no cupping or any problems, even wear. good enough that tire place bought them from me to resell.

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Originally Posted by Ldub

:fyi:...you should always have your best tires on the steering axle, so blowouts, however unlikely, are more apt to happen on the rear axle.

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True ... but ... for the sake of the TOD, I left 'em up front.

Quote:

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Originally Posted by tom4bren

I'd always heard that cupping was caused by bad shocks.

As far as offset is concerned ... mine have never shown any cupping but with MTs, it may be hard to tell. My fronts are VERY worn (but evenly) while the backs are still good - rekin I shoulda rotated more often but by the time I noticed it, it was too late.

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Insert 2cents:
Yes, usually a indication of the tire bouncing, plus with the under pressure would increase the problem.

Quote:

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Originally Posted by Ldub

:fyi:...you should always have your best tires on the steering axle, so blowouts, however unlikely, are more apt to happen on the rear axle.

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Why have the best (Isuppose you mean deepest tread) on steering axle ie front when manual calls for taller tires to be on the back refer to manual mini spare goes on front even if flat is in back you should put mini on front and move full size to back.

Quote:

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Originally Posted by tom4bren

True ... but ... for the sake of the TOD, I left 'em up front.

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Quote:

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Originally Posted by circmand

Why have the best (Isuppose you mean deepest tread) on steering axle ie front when manual calls for taller tires to be on the back refer to manual mini spare goes on front even if flat is in back you should put mini on front and move full size to back.

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Good points both, I guess I hadn't thought it through that far...:mbrasd:

Since having those dodgy ball joints on for a while i have really a reall worn outer edge on both front tyres, i've swapped them to the rear now which makes traction in the wet fun but there must have been an inch difference in diameter !! I need to adjust the camber of the front wheels, i just dont have the time to do it!!!

Doing a lot of inner city driving, another thing that can be a burden on front tires (other than alien alignment), is the excess turning the vehicle does. Especially AWD and FWD vehicles. Torque-steer puts some stress on those fronts and wear is always greater than the rears. A slight misalignment in the front and you are looking at quicker wear. Because of our wheelbase, torque-steer always seemed a bit high to me, especially on peddle mash on a turn-from-stop. Something to keep in mind since many people never even realize it. ;)