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-   -   255s on 8.5" Rims for racing? (http://forum.e46fanatics.com/showthread.php?t=844715)

z_man93 05-17-2011 05:33 PM

255s on 8.5" Rims for racing?
 
I'm trying to come up with a track setup that is decent and affordable. I have qty6 M68 wheels already, so it's a sensible choice to go with considering the 8.5" wheels are only around 21lbs. I've only done 6 autocrosses over the past year, so I don't need anything extremely competitive. I'd rather spend my money on more seat time. I am however driving at the limits of my current setup.

I'd like to go with a square setup all-around with my M68 8.5" and wide-as-sensible Star Specs. I'm trying to do as many AutoXs as possible and also fit in a couple NASA HPDEs this summer. For SCCA STX the widest tire I can go with is a 265. I couldn't imagine fitting a 265 on an 8.5" wheel so I'm leaning towards a 255.

My question is whether or not a 255/40/R17 is too wide for an 8.5" wheel for competition driving? That's ~.75" overhang on either side.

BartenderPlease 05-17-2011 05:51 PM

That size will work fine. I used and abused a 255/40/17 on my rear m68's. They were BFG, which ran much noticeably fatter than OEM 335i sport tires (255/35/18).

Do it :thumbup:

LivesNearCostco 05-17-2011 08:38 PM

That is what I did for AutoX--255/40/17 Hankook R-S3 on 8.5" rims. They don't look too wide, but I haven't driven them in any events yet so can't say. I'm signed up for the BMW CCA AutoX this Saturday at Qualcomm, so maybe my new tires and I will see you there? (I don't do SCCA yet.)

I've seen this question come up a few times in the track, AutoX and club racing forum on bf.c. Half the respondents say what BartenderPlease did--Do It! The other half say 255 width tires feel more precise and grip better on a 9" rim and you should not run more than 245 width tires on an 8.5" rim.

2003 325i 05-18-2011 01:50 AM

255 is an OEM installed width tire on most BMW 8.5" wide rims. I don't see how/why it'd be a problem. 255/35 R18s came on the rear of the style 293s I bought from a Z4 owner, 8.5" wide.

woorick 05-18-2011 03:35 AM

Quote:

Originally Posted by 2003 325i (Post 13180386)
255 is an OEM installed width tire on most BMW 8.5" wide rims. I don't see how/why it'd be a problem. 255/35 R18s came on the rear of the style 293s I bought from a Z4 owner, 8.5" wide.

My impression on factory sized tires is that usually performance cars will have a staggered setup vs. a square setup because it would make over steering less likely. On a staggered setup.


Sent from my DROID2 using Bimmer App

VMRWheels 05-18-2011 02:00 PM

Quote:

Originally Posted by woorick (Post 13180507)
My impression on factory sized tires is that usually performance cars will have a staggered setup vs. a square setup because it would make over steering less likely. On a staggered setup.


Sent from my DROID2 using Bimmer App

It's somewhat cosmetic as well. ;)

Some people like seeing the rear wheels a bit more aggressive than the fronts, but for every day driving I'd say staggered is a bit safer.


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