Hi All,

I am researching tire choices for the upcoming auto cross season with the SCCA's BStock class. I am looking at Hoosier AS04's in 245/40 X 18 on stock Rims front and rear. I have a Hotchkis sway bar on the front (changing rear is a no no if you are staying stock) witch increase stiffness by 7% on the lowest setting. I am thinking 245's on the front and rear will give me a few added benifits.

1. More Balance without the staggered offset

2. Less understeer with more traction going to the front tires over stock 225/45 18 sizes

3. Handle a bit better with the overall increase in grip via transfer of cornering weight to the front of the car

4. Run a touch quicker due to the smaller overall tire diameter. 2.3% Smaller on the rear

Am I wrong on any of these assumptions?

Should I go with a 275 - 35 18 In the rear or will i have re-introduced the understeer?

My overall tire costs this season are going to hit 5000$ with replacing stock Pilots, and purchasing a dedicated set of racing tires and wheels so I need all the advice I can get.

Thanks,

 

A friend/aquaintance who I see at the monthly auto-cross's drives a 2003 Z and he uses Hoosier 245's all the way around. He loves em'. He also finishes 1st or 2nd overall every time. He's bone stock!!! besides the tires. I tried race tires last season, and though they helped my times, I didn't like the extra hassle of lugging them around, etc,etc...

 

I am running 275 V-710's. Very nice. The rounded edge of the tire helps with our camber challenged front-ends. They are a tight squeeze on the rims, but they seem to work well. You end up with more rubber on the road than the Hoosiers at 245. One driver did a test at the last winter event. Ran Hoosiers and V-710's, same size, back to back on the same car(not mine), same course and same driver(awfully good driver). Times were within 2 tenths. Tires appear to be equivalent to one another. Turn-in is crisp, but you don't get a lot of warning when the tires reach their limit. You can adjust for any understeer with pressure changes. My car handles very neutral with no change to the front sway bar. If you are new to autocross, you might want to learn race rubber with a more forgiving tire like the VictorRacers. They wear well, are more forgiving and are cheaper if you flat spot them by doing something stupid ( I have been there myself). I am probably going to upgrade the shocks next, rather than a sway bar in the front. By the way, the Hoosier SO5's will be out shortly. They could be the tire to beat this year, if Hoosier has anything to say about it. They were not too happy about losing so many events to Kumho.

 

Thanks for the reply's, In the end I went with 245/40-18's all the way around. I figured that would make the car more neutral. I played with the idea of Kuhmo 275's rear with 245 hoosiers up front but figured the 245/40 hoosiers were a known quantity and if they didn't work I could always try something new. As for the AS05's the AS04's were so cheap last week I couldn't resist. 800$ installed. Ill let you know how they work next month.

What shocks are you looking at? I am thinking of splurging on some Koni's. I think it could make for a mean setup. Any shockingly good ideas?