Hoosier R6 on gt2 oem wheels. they are a little heavy but i wanted 12" rears

 

Hey Gunther, Just curious what neg ft camber are you running when you have understeer on the PS cups in stock fronts? I run neg 2.4 ft and neg 2.1 rear with hr sways full soft front and medium rear and have dialed out the understeer. I think I also start cold 27 ft 29 rear.

Sorry didn't mean to take us off topic or hijack the thread.

 

Nitto sizes are generally 235/40/18 front, and 315/30/18 rear. I run a 245/30/18 up front, which is still within the rolling rpm parameters, and it gives me a little more grip with no problems from the front diff. Some guys run 265's up front on 9" rims, don't know if Nitto makes that size.

 

Hollywood, I do not know what my alignment specs are. But could ask and get back with you. Yes, I'm running stock turbo twists with 225's at 28lbs of air on the front. In the rear 295's and 35lbs of air. I need to fool with tire pressures more to see how that effects the setup.

Like Landjet says above I will be trying to get some GT2 (8.5 inch rims) front rims to try and run the 265's. I know a few other board members running the 265 and 315 set up on 18's and they really like it.

 

I would recommend getting the maximum negative camber you can get,
and leaving it that way. I would change to the wheels/tires I wanted for
the driving I'd be doing, and just accept the tradeoff of inner-edge tire
wear when commuting, in exchange for better cornering all the time, and
better tire life when doing a lot of hard cornering. I'd even rotate the tires
on their rims when/if I saw the inside edge getting more worn than the
outsides.

 

Basically you want to be no larger than 25.5 - 25.6" or you could rub on full turn. Tirerack lists the diameters of all tires and shows the range of wheels they should be mounted on. As long as the front and rear diameters are close to the same size, it works within reason. That is what I was referring to. If you use TR's standard stock sizes it will not show you options like the 235/315 combo mentioned here. I know for a fact that combo does not rub. Going wider in front can require some adjusting although I hear of people running 245's with no issue.

 

I have a C4S so I have the same issues with tire sizing.

That's exactly what I do as I daily drive my car and autocross it regularily (2-3x's month) with local GGR & LPR PCA, and GGLC (Lotus). I had the tires flipped on the wheels a few months ago as the outside edge will wear more as you are limited to the amount of camber you can run with the stock settings. The most I could get is -0.7 F & -1.5 R. I don't want the hassle of changing wheels everytime I go autoxing and I want to stay in my current autox class, so I run tires as close to a 140 treadwear class limit. This also works well as I have streetable tire for daily driving, but in that treadwear range they are still fun tires availabel for autox. So you may also want to consider what class you want to run your car in as tire choice will probably come into play.

I'm running Yokohama AD08's and was going to stick with them until I found out today that they are backordered and it'll take over a month to get them...which led me to this thread searching for other options. It's rather unbelievable to me still but I got 15K mi out of the rears (they look like slicks after this weekends double header autox) and the fronts are just about to hit the wear bars. Previously I went the cheapo route and had Kuhmo SPT's and Sumitomo III's. They didn't last any longer, and were at least 1-1.5sec slower autocrossing. I just ordered some Kuhmo XS's in the sizes Nikolas mentioned. The Falken 615K looks like it could also work in the 235/40 and 315/30 sizes, but I haven't found anyone running them yet in this application to double check the fitment.

 

Joe,
Thanks for the help.
I got to autocross the car this last weekend at Marina. I used the stock tires. I had a blast. But now I have a lot of questions and you are the autocross king so..

The car has a lot more understeer than I expected. I was able to lessen it by backing off the throttle a bit, but it was still pretty pronounced. Should I expect that with this car? (my boxster cornered quite a bit smoother.) Will a wider front tire help with this or should i just get new set of tires all around?

I have been looking for the kumho 710, but i dont see them in a stock size at kumho.com or tirereck.com. I do see these; http://www.tirerack.com/tires/tires....&autoModClar=e
they are pretty cheap, but i dont think they are the 710's

What size kumho 710's can i get that will fit this car?

Also, I am going to get the pss10 suspension this fall sometime. How much will an aftermarket swaybar help for autocross? Or will it hurt? I am thinking that the pss10 should help my overall ride quite a bit, help autocross a little, and help DE a little. Do you have any thoughts?

Thanks again.

 

Hey Kevin,
I was parked next to you at Marina this weekend. Any update on your tire search? I noticed you still had the old tires mounted.
Scott

 

Hi (thanks!) yes, you should expect understeer until you get negative
camber and a wider front tire. The win-at-all-costs tire is the Hoosier
AS06. The almost-as-fast-and-last-a-lot-longer tire is the Kumho 710.
I drive those to, in, and from events. Below those are tires like the
Yokohama A048, and then I'd look at the Yokohama AD08. Yes, you have
to juggle a just-too-wide-for-the-rim, or slightly-narrower-than-you-want
tire to keep the front and rear rolling diameters close. If you have adjustable
swaybars you can loosen the front or tighten the rear too...

 

Hi Scott, I didn't occur to me until you'd left that maybe you were from the forum. I got a set of Kuhmo XS's that I need to get mounted. Hopefully I'll be able to get that done before this weekends GGLC event.

 

Joe, I am having trouble finding the proper size kumhos. What size kumhos can i run on the stock rims without rubbing ? Or where can I find that out? ( I see that you said they were street legal above)

Thanks
Scott

 

PSS10's are too lightly sprung for the track, I know because I had the PSS9's which are basically the same, before I upgraded again. Autocross and street are OK for the PSS10's, but you will not be happy with their lack of control on a high speed course.

 

Scott, for stock wheels you want these Kumho 710s:
245/35R18
285/30R18

 

I ran recently
225/40/18 fr
305/30/18 r and they worked out great, very sticky, could of used a little more width in the front, thinking now of 245/40/18 & 305/30/18 less than 1% diff, only question has anybody ever run 245 on 8" wid? recommended width is 8 - 9.5 ?