Which set-up???
 

Hi Gang...

I'm trying to set up the tire and wheels combo for the track.... need some suggestions!

Should I go with 225/45/18 front and 245/45/18 for the rears or use 245s all around????

It takes forever for the TOYO RA1s to come in so I gotta make a call SOON!!!

Please help!!!

I would probably recommend going with 17's instead of 18's for lower unsprung weight and rotational inertia. It would also make size selection better as their are more options in the way of 17 inch R-compounds than there is for 18 inch.

Also for the most neutral handling possible I would say run 245's at both ends if you can fit them without rubbing. Putting 245s out back and 225's in front would lead to more understeer.

I always heard go with the base setup when upsizing, i.e. if you have a 215 front / 255 rear and you want to upsize, then try a 235 front and a 285 rear.

Cars like our 8 have the same widths front to rear, so increase both the same. If you go with different sizes, then you better be willing to do suspension work to "re-balance" the suspension. Otherwise, if you got the rear sticking better with a wider tire, then expect greater understear - with no suspension work.

Just my 2 cents. I suspect the 8 may be soft for serious track work, but perfectly balanced for an aggressive drive.

Suspension I'm using is the Mazdaspeed system...

Let's say I was to go for the same size.... on the RA1s there's 245/45/18 available...that's the size I should go for then??

Why dont you give Speed Source Inc a call. They have raced RX-8's in Grand-Am cup very successfully and I believe they run on 17's. www.speedsourceinc.com

Checking SPEEDSOURCE's website all weekend, and they DO run 17s but not sure which size tires they use!!!!

Call them at 954-578-7071, they might even have used hoosiers you can buy cheap!

thanks #84

not sure what kinda suspension they are using but they use thicker sway bar at the front and 245s all around but STOCK rear sways to keep the car nutural!

I have the complete mazdaspeed suspension and for the track I use 17X8 ROH Drift R wheels with 245X45X17 yokohama advan 032r soft compound tires at all four corners. The offset on my wheels (sorry dont know what it is) widens the track about an inch and a half which also helps. I find the setup is amazing.

CDOVE - i believe that's the same tire size to the SPEEDSOURCE 8s.... and they do great on the track! btw.. which MS suspension system do you have? the coilover or the shock/ springs?

I have the shocks,springs, and sway bars