so, im slowly pushing my car into roadcourse racing. i've got plenty of suspension and chassis work done, but now im wondering about the tires.

can i go 315 in the front of my '02 GT? is there a minimum or maximum offset i need to use to get it done?

im lookin at using bullit styled 17x10.5's right now, with a 25mm offset on some 315x35 series tires. will it work without rubbin? i know the rear ends fine with that combo, but will the front work?

im all about stickin through corners, and in my class my car already pulls through every turn. with the 315's up front, im hopin i can completely get rid of any oversteer.
without gettin riding of all the rubber in my front end, im out of options here for cornerin speed, and these 245's im runnin now arent cutting it. obviously.

thanks,

chris

 

I have no clue how to answer this question, but I have never heard of anyone running a 315 up front. You will most likely have severe turning issues, if the wheel will even fit.

That's all I have to say. I'm an idiot when it comes to suspension and **** like that. Maybe someone who is much more knowledgable in this area will chime in.

 

You could do 275's up front and have no fear of rubbing...

 

You won't be able to ge a 315 on the front 275 is the best you can do without modification and even then you might rub depending on what suspension mods you have

 

I thought the max wheel width you could have in the front was 9"
... maybe that's just my year, I haven't really looked into 98-04 models

 

I think your best bet is to talk to the guys at Maximum Motorsports, Agent 47,or Griggs racing. The widest suggested wheel size for a stock 02 is a 9" wide wheel with a 275 tire and even those can rub sometimes at full lock. Chances are that you don't have a need for that wide of a tire though. There is a HUGE difference between street tires and R compound tires. If you are serious about racing check into them, a 275 hoosier R6/A6 is going to be worlds apart from any 245 street tire (I am assuming you have street tires). Keep in mind that puting too much tire on a car while you are learning to race is just a bandaid and will hurt you in the long run by creating bad driving habits. Also if this is more of a race car than a street car you may want to get something lighter than a Bullitt style wheel. Just my .02

 

definitly started looking into better composite tires. thats lookin like the ticket right there.

as far as the band-aid thing goes, its not that at all. im sideways through my turns as it is, and yeah it looks cool, but its slow. exit speed tends to be pretty shitty when your tires are spinnin comin out. my real concern was the longevity of expensive *** tires. i would like to be able to rotate and get a few track days out of them.

i'll post some pics as soon as soon as i get back stateside. along with the upgrades list, but i've got a few months left in this deployment, so it'll be a little while.

thanks again guys

 

First, 315 tires in the front is possible. There are plenty of racers that use massive tires, Ernesto Roco, Paul Brown, several other AI racers and even my autocross coach. However, you need to ask yourself if 315 tires are the right step. You said you were trying to eliminate some oversteer. Wider front tires are only going to make oversteer worse. Bullitt style rims are not a good choice for racing or trying to run 315 tires up front. You should be using r-comp tires before you consider running a 315. Also, what braking system are you using? You got to think about if its really needed. When proffesional racers and cars with 800+ horsepower are using 305 and 315 tires in the front, I know that I'm only going to need 275 for a while.

 

If oversteer is a problem when you start the turn then try a slightly lower spring rate in the rear or if it's breaking loose after you're already in the corner under load then a lighter duty rear sway bar should help. Wider front tires will exacerbate the issue. If you need more grab in the front you play with the front. If you need more grab in the back you play with the back. Most guys I race against are using way too much spring and sway bar. If you're not brushing the bumpstops on the sharpest turn on the course you're using too much spring/sway.

Look at 01fr500's sig pic... you see his driver front wheel lifting and the passenger front and rear at maximum compression, that's a well set up car being driven at its limit. You can do that on street tires. R compounds are fantastic after you learn how to drive that well but they'll slow your learning if you jump on them too early.

Here's a pic of me crushing the driver side suspension as I start a turn
http://s56.photobucket.com/albums/g1...t=SA400065.jpg

and it flattening out as I give it the whip at the apex
http://s56.photobucket.com/albums/g1...t=SA400070.jpg