Scangauge recalibration - Tire size increase

Hey guys what's the percentage increase I need to set my scangauge to?

Going from Stock size, to 33" tires?

Thanks!!

Richie

(I searched the forums... really.. couldn't find anything)

Hey Richie...

I've done measured mile speed/distance checks over a 4 mile section of f/way...

...and my 33's seem to give a little under 10% differential.


jo

do the math: if the diameter of the original tires was 24
inches and the size of the new tire is 30 inches, 100x(1-(24/30)) = 20.
Setting the value to 20% will compensate for the tire size change.

right, the 10% Jo quotes sounds about right. My 31.5" tire is 6%

Only problem is I don't know the stock tire diameter. I had a different size on my VX when I bought them.

It's printed on the inside door though if I remember.

I just asked this question like a month ago.

http://vehicross.info/forums/showthread.php?t=13532

I think mine comes out to be about 7% off. So, at 60 on my speedo, I am most likely going about 65. I need to set my scanguage up to calculate this, just haven't had the time to dig out the instructions. If you figure it out, post it up if you can....

Bart

The stock tire is 30.5 inch dia. according to http://www.miata.net/garage/tirecalc.html

Richie,

I'm running 33's. TomTom tells me the speed is off 'zackly 10%. I'd start there & adjust as necessary.

Tom

my stock tire size is 29.5... 245/60/18

Stock tires on the 00, 01 are 245/60 R18 = 29.6"
(all sorts of neat info on the Federal Sticker in your drivers door frame.)

Mine are 265/70 R17= 31.6"

My Garmin tracks me at 10% error. Doing 66mph by GPS when speedo says 60mph.

Thats right, I knew that 30.5 didn't look right. For some reason I was thinking they were 265, me dumb. Thanks for correcting my boo boo

Hi Guys: If you want quick and accurate Tire Size Comparisons which also gives you the approximate differance in your speedometer -- go the the website of DISCOUNT TIRE on the web and then click on their TIRE CALCULATOR. It is truly amazing and takes all the guess work out. Type in the OEM Tire Size (found on 2000 & 2001 VX's) of 245/60R18 and then compare the differance to another size of interest. Incidentally, the tire brand that has the most diverse sizes of off-road tires that fit the OEM 18"x7" rim is: TOYO - OPEN COUNTRY A/T and M/T. Go to the TOYO TIRE website and print-out their size chart for the OPEN COUNTRY. You'll be impressed!

the tire calculator at discount has my calibration off by about 10.6% ;) I've been running my scanguage at 10%.

Direct Link: http://www.discounttire.com/dtcs/infoTireMath.dos

why not properly recalibrate your speedo :rolleyes:

you know the wrong size also screws up your odometer and trip meters as well.

check the back of the gauges and look for an adjustment potentiometer, failing that change the gear on the speed sensor (costs $8 you subtract 1 tooth for every 3% gain you'd like)

failing that you can can get a digital adjustment module from Dakota Digital.

Dakota Digital SGI-5:
http://www.dakotadigital.com/index.c...rod/prd126.htm
That thing will let you tweak your speedo exactly.

When I'm driving, the last thing I want to do is math in my head to figure out what my gauges are saying

Um scangauge does the math for you.