itsphoenix

I looking at getting Nitto NT01's for my C4S. Does anyone know if 245/40/18 front and 315/30/18 back will fit on the stock rims. I am concerned about tire rub and the all wheel drive system. I have heard that if the size is off it can damage the diff?

Thanks

Byprodriver

Try Nitto website to see if dimension's are posted. diameter & revolutions per mile are critical for AWD.

LVDell

You want the 235/40/18 and 315/30/18 setup. Worked like a champ on both my GT3 and Turbo!

Diameter is spot on at 25.39 and 25.35

And yes, those are on stock wheels.

mglobe

You've got a 4S, right? Even if you don't, I would think carefully before going to that much rear tire. You really don't need that much rubber to put the power down, and you will accentuate the understear that is built into the car. FWIW, I run 245/285's on my race car. You may not want to go to that low a front/rear ratio, but I personally think 315's are too much tire. ymmv...

btw, if it is a 4S, matching front/rear diameter is a very good idea.

LVDell

The problem is the next size down is a 275/35 and that really is too small.

mglobe

You might be surprised. I've run 275/245 in NT01's on my car. They work fine on my C2. I don't really understand why a C4 would need more tire. 315's are going to make it very hard to rotate the car.

itsphoenix

I am running a 4S. If I run matching fronts and rears what size tire should I run and will they fit the standard Turbo & 4S rims?

Thanks

LVDell

Without knowing the OP and his ability on track, there is no way to determine if he wants to rotate the car (more oversteer) or have some understeer dialed in. And yes, I agree, you can go fast with smaller sizes. I ran my fastest times at VIR in my GT with 250 fronts and 280 rears. A crapload of oversteer but that was fine by me

For mr. phoenix..........please get us some more info about what you want to do with these tires? I'm assuming this is for a track event not the street correct? What level of driver are you? Anything else and we could give you some better help on tire selection. I can tell you I have tried just about every track tire and brake pad combo out there and there are others like me on this board so use that knowledge base.

itsphoenix

Thank you all for you input and time on this. The tire and wheel setup will be for track use. Currently running the stock continentals the car is understeering in the sharp turns, not allot but enough to try to correct it. I have no oversteer at all. The tires are great for the first two or three laps but then the understeer comes in play. I have been playing with tire pressure and it does not help. I am not looking for oversteer just less understeer. The car is extremely planted and predictable.

As far as my driving abilities I am a upper novice. When it comes to lap times I was able to do 1:19 all day on stock tires. To compare that with other drivers with much more experience driving M3 BMW's on track tires they are getting the same lap times.

I am not looking to become a race car driver just looking for less understeer, better and more consistent grip while not burning through my street tires.

Thanks

LVDell

One thing that might help much more is ARB's. Do you have the stock ARB's? If so, moving to the GT3 ARB's would be a huge help so you can actually dial in front/rear behavior commensurate with under/over steer.

I would do the 235/275 or 235/315 combo but know that ARB's will help you more than tire pressure and tire size. Also, alignment is another thing that needs to be examined. If you have a stock suspension then you are going to max out at 1 degree or less of camber up front and no matter what you do the car is going to push like a dump truck.

Optical TDI

+1 here. I put on a rear H&R bar and it has made a HUGE difference in how the car feels and it will rotate now easily throttle oversteer on slow tight corners. With the stock bar it was very hard to do that due to the understeer. Best $230 I spent on this car so far. And a snap to put on too!

mglobe

Is the car then primarily a street car? And will you be driving to and from the track on the tires you use at the track?

itsphoenix

I will be driving to and from the track. But these tires will be on different rims so I will not drive on them every day only the 8 miles to the track

mavthenav

Nope that's what I have on my rear and I tell you it sticks like glue, but I just have a c2

LVDell

Apples to Oranges. lightweight narrow vs. heavy *** wide body.