Help with tire/wheel ?'s for a newb

[ConeKillinGoat]

First off, I want to say I probably had the most fun I have had in a car on Saturday. I've only drag raced before and was surprised auto-x was so much more fun. Anyway I am addicted now and have some questions for some more experienced auto-x'ers. If anybody watched me run Saturday, in the black GTO, it’s obvious I am gonna need some stickier tires, and probably a lighter foot. I was more in a drifting competition than auto-xing, which was fun but slow. My question is I am currently running heavy chrome 19x8.5 with 245/35's up front and 19x9.5 with 275/30's in the rear with crappy 400 treadwear tires. I have a significantly lighter set of 18x8 wheels I could buy tires for, which would have to be 245's all the way around. Would I benefit enough by smaller stickier tires or should I bite the bullet and buy another set of staggered wheels. Also, what are the tire restrictions in the SM class? I realize I am probably on my own as far as test n' tune since I am driving a heavy car that is not really designed for this. But I am hoping some of ya'll can help me from wasting too much money. Thanks in advance for the help and sorry for the long post.

[nicktcr]

Glad you came out and found a more enjoyable form of motorsport than flooring it for a few seconds

I am also glad to hear that the FIRST change you're wanting to make to your car is undoubtedly the most important one you could; better tires!

If you can afford to just buy wheels/tires dedicated to using only for racing, a smaller diameter wheel will be cheaper, lighter, and will cost you less on tires. You'll want to get the widest allowed for your class/car dimensions/budget as well, to fit the most amount of tire allowed for with the aforementioned variables.

As far as the SM class goes, I am not sure of the (if any) wheel/tire limitations and will have to let someone else speak to that. Did the car come factory with staggered wheels/tires? If so you may want to try to retain a similar balance. If not, then going with an even setup may be fine, and some nice new sticky competition tires will certainly benefit you much more than whatever you drive on day to day.

Welcome to the board!

[ConeKillinGoat]

I already have a set of 18x8's I could use that are BMW M6 replica wheels, which are the same size that came on the car from the factory. It would be a lot cheaper to just buy tires for those, but I'm wondering if I would benefit enough to justify the extra expense (probably $750) to buy another staggered set so I could run 275's on the rear. Also if there are no limitations in SM, what tires would be the best for a heavy (3750lb) 400hp car.

[nicktcr]

Stick with what you have, for now. That makes sense. Come out to a few more events and make sure you're really committed to doing this before spending tons of money on more parts.

As far as WHICH tires to pick up, you have a few options. This is the part that takes a little research, and you will hear a dozen different opinions about each tire if you ask around enough. I'm going to try to give my most neutral answer for this one:

The popular, and generally accepted "best" tires (based on grip levels, tread life, legality, cost, etc) are as follows: Dunlop Direzza ZI (and the new ZII), Kumho Ecsta XS, Hankook Ventus R-S3, and maybe the Toyo Proxes R1R. I THINK the preferred tires for heavier cars are the Dunlops and Hankooks in our area with our hot summers. Again, it will depend on who you ask and what they drive, so keep an open mind while researching

[ConeKillinGoat]

In the SM class do I have to have 140+ treadwear? I tried reading the rule book on the scca website but it refers to the Street Prepared, Street Touring, and Stock. Going back and reading those it looks like it has to be 140+, I just want to make sure I'm reading that right.

[JohnW8]

Stick with what you have, for now. That makes sense. Come out to a few more events and make sure you're really committed to doing this before spending tons of money on more parts.

As far as WHICH tires to pick up, you have a few options. This is the part that takes a little research, and you will hear a dozen different opinions about each tire if you ask around enough. I'm going to try to give my most neutral answer for this one:

The popular, and generally accepted "best" tires (based on grip levels, tread life, legality, cost, etc) are as follows: Dunlop Direzza ZI (and the new ZII), Kumho Ecsta XS, Hankook Ventus R-S3, and maybe the Toyo Proxes R1R. I THINK the preferred tires for heavier cars are the Dunlops and Hankooks in our area with our hot summers. Again, it will depend on who you ask and what they drive, so keep an open mind while researching

I don't think SM is limited to only 140 tw street tires so an option of using R-Comp tires like Hoosier, BF Goodrich, Toyo and Kumho are available but be warned they are very addictive and wear very quick. 30- 50 runs are a ball park average but could be less with a heavier torquey car like the GTO. Nitto NT01's are also a popular tire due to their R-Comp like grip and street tire wear. Also keep in mind that as easy as it was for you to roast the tires on the heavy 19" 275's a 18 " 245 will spin easier due to the smaller contact patch and lighter wheel. I think I'd try a stickier street tire first on the 19" wheels you have and modulate the throttle a bit, scratch that, a lot more. Ride with Brandon in the silver corvette if you get a chance and watch how he controls the throttle through the course.

You looked like you were having a blast! Welcome!

[ConeKillinGoat]

Thanks for all the responses, I think I may just try to sell my 18x8's and find a cheap set of staggered 18's to put some stickier street tires on for now. I drive too much with my job to drive on them everyday and auto-x. And I would love to ride in that silver vette if it were possible. I'd like to see gear selection and throttle control. I tried in first and second and spun in both. Although truth be told, I was enjoying walking the car with it spinning too much to try too hard not to break it loose. It was more fun to drive that way, but not much fun to see the times I was running.

[Cholewa]

I would work on learning to control the car (the power) with the 400tw tires before making the jump to stickier tires. The better the tires, the more they cover up driver error, and you don't want that. You want to be able to learn the finer points of controlling your car, and the best way to start, is by doing it with terrible tires. Every mistake you make will be obvious, and you will quickly learn what is necessary to fix those mistakes.

Stick with the 400's for now, get a codriver, ride with the vettes, and just generally get a better idea of how to autocross (the mindset), and all the rest will follow.

[JohnW8]

I would work on learning to control the car (the power) with the 400tw tires before making the jump to stickier tires. The better the tires, the more they cover up driver error, and you don't want that. You want to be able to learn the finer points of controlling your car, and the best way to start, is by doing it with terrible tires. Every mistake you make will be obvious, and you will quickly learn what is necessary to fix those mistakes.

Stick with the 400's for now, get a codriver, ride with the vettes, and just generally get a better idea of how to autocross (the mindset), and all the rest will follow.

Good advice. Although torque and 400tw tires make for a frustrating day. I can spin my new 400 tw tires with my piddlin' 107 lbs/ft torque. I would be mighty frustrated with 4 x that torque and trying to go fast. On the bright side, with all the tire spinning you will be looking for new tires soon.

[Cholewa]

Good advice. Although torque and 400tw tires make for a frustrating day. I can spin my new 400 tw tires with my piddlin' 107 lbs/ft torque. I would be mighty frustrated with 4 x that torque and trying to go fast. On the bright side, with all the tire spinning you will be looking for new tires soon.

Yeah. The throttle becomes an on/off switch. It's a great chance to learn the finer side of throttle modulation. Probably still can't just mash the throttle even with star specs, too much torques.

He's at least got the advantage of wide tires, even if they aren't sticky they're not like 205's all around or something equally silly (like my friends GTO had).

[ConeKillinGoat]

I may have added to my problem too by over inflating the air bags in my rear springs. I was thinking body roll would be my main problem so I was running 18lbs of pressure when I normally run about 12 on the street. The rear end was too loose for body roll to even be an issue. Transferring a little weight may have helped with my traction. Next time I may start out at 16 and drop it from there. It also didn't help that this was the first time I've been able to drive this car at more than half throttle without worrying about a ticket or putting it in a ditch. Maybe I got it out of my system so next time I can concentrate on going faster (or less slow) instead of just having fun.

[nicktcr]

Maybe next time I can concentrate on going faster (or less slow) instead of just having fun.

That's well and fine, but don't forget to have fun

[Cholewa]

I'd be more than happy to codrive with you and see if I can give you some pointers on the current setup.

[kilgojr]

I'd be more than happy to codrive with you and see if I can give you some pointers on the current setup.

[Cholewa]