I knew that would suck you in.

The question is about tires. I am getting ready to put on some new rubber (replacing my SO2's at 10K) and am wondering if there is any good reason to put on oversized tires? I know some guys do this and I am wondering if it just bling or grip. What are the tradeoffs? Safety, stability?

I have GT3 wheels with stock 225 front and 295 rear. Can/should I put on 235 and 315's? I run the car pretty hard and put in my time at the track.

I also welcome any jokes or peverse thoughts you might have had after reading the subject line.

 

You mean, I can't comment on how "size matters"??

Wouldn't placing a larger tire (235 or 245) up front assist alleviating some of the understeer?

One last thing...and something I just found out the hard way. Some wheels can handle a larger tire up front (apparently). I could have gone with a 235 easily with my Kinesis wheels as the PS2 225's look "stretched". My Conti 225's were just fine, the Michelin's look odd. I'll be going with the 235's next time providing I stick with this tire.

 

Size does matter; that's why I need the larger rubber.


Any one know the size limitations of the GT3 wheel?

 

Tal, The front GT3 wheel is 8.5" wheel wide and will accomodate a 235/40 or 245/40 18 OK.

Rim range for 235 is 8-9", and for a 245 is 8-9.5"

 

Actually, alignment and suspension settings are the way to go when chasing handling issues. Adding tire contact area isn't effective on its own, because in order to build up sufficient heat to increase grip, you also have to add more downforce. For this reason, some identical race cars actually turn faster lap times with a slightly narrower tire than a competitor, depending on the downforce set-up used for that particular track. Confusing? Don't worry about it. Keep in mind that the GT3 and TT have been tested extensively by guys like Walter Rohrl for Porsche, and most mortals will never exceed the performance capability of the stock set up.

 

if u're running stock wheel i wouldn't suggest u to run anything beside the factory N-spec tires.

 

Hey ARling does that go for rear tires as well? I am gonna need a new set of rears and I was thinking of something a little wider and maybe taller...ideas? it will be on 18x10 Carrera Lightweights...

 

Btw, if you have to ask if you need the oversized rubber, you don't.

 

Run 245's up front. I couldn't get bigger than 295 on my rears.

 

why?

 

I'm running 235/315 (GT2 spec Rossos) combo on my 996 Turbo with stock 8"/11"rims. They fit fine with no spacers. I believe they have some advantage for street use. The more rounded sidewalls give more curb and pothole protection and ride smoother. The speedometer reads 2% slower (more accurate). They look better. The downside is maybe slightly less sharp steering response, and the car sits 1/4" higher. The gearing is 2% higher. The understeer seems about the same as the standard size tires. I may go to 245 fronts if the 235's ever wear out.

 

With really wide tires it actually gets annoying. You have a big contact patch, but you get stuck in the grooves of the highway. Its like steering a train, it will go where the tracks take it.
-Daniel

 

The condition is known as "tramlining", and is very common on some cars. Sometimes staying away from directional tires fixes it. It varies from car to car. I have heard on numerous occasions from people who have gone from 225 to 235 on the front that it creates the condition.

Read up at:
http://www.tirerack.com/tires/tirete...tramlining.jsp

 

I have 225 and 265 on stock wheels - 99 996 C4. Whats the widest I can fit on this setup? - I figure 235 on the front but can I get 285's on the back? - Also should I get a taller tire to fill in the gap? - I have MO30 suspension kit but this did not lower the car all that much.

 

In my experience trammeling is worsened by wider front wheels, more outboard front wheel offset, the tire sidewall construction, shorter sidewalls, and front toe-in not at optimum. Small trial and error changes in the toe-in can improve it a lot.