Is there anything to gain by going with a 235 (or 245) 245 front tire (all else equal

I'm checking out the tirerack site and weighing my options. I'm used to bmws with the 50/50 balance. With those cars, going to a wider front tire vs. stock (while leaving rear alone for example) resulted in better cornering grip. However, with my C4S and weight in the rear, i'm wondering if the effect would be as great. The car obviously already handles great, but is there much to gain by deviating from stock tire sizes? If stock is 295r/225f, will 285r/235f be a more neutral car without adjusting anything else? I realize that with great downforce or other modifications, more front tire would be beneficial. But I'm wondering if there would be any gain without those further modifications. there really are a lot of tire options and even more when playing with tire size. Please educate the rear-engine virgin... thanks in advance.

I did that on my Boxster S because it was understeering in excess. I went 265/35R18 all around on MPSC for the track, and 245/35R18 all around on Hoosiers for auto-x. You have the understeer experience on the E46M3, I guess. Understeer in C4S is not as bad as the M3, but it's still there. Decreasing rear tires width to promote oversteer is a bad practice. You have to increase contact patch all around while trying to achieve neutral handling. This is done by choosing tires width, corner balancing, sway bar adjustment, wheels width, ride height and camber. My recommendation is to go 245/35R18f and 295/30R18 rear if using 8" front wheels . Increase 1 degree more of negative camber at the front, and you will stay with minor understeer (under heavy turning). BTW, how do you like the PSE compared with the exhaust sound of the M3?

I wouldn't change your tire sizes unless you were having too much understeer under hard driving, i.e. track use. I also came over from an e46 M3, which understeered too much. The 996 is a different animal. I'd get to know its limits before making tire changes. I liked the "wrasp" of the e46 M3 exhaust, but allot of folks thought otherwise. I find the 996 exhaust note under hard acceleration to be much softer in quality.

thanks for the input. i thought I'd run stock sizes anyway until I felt the need to do otherwise. With the M3, there was more of a popular 'hot' setup for tirewidths instead of stock. On both 18s and 19s, many ppl went from stock (255r/225f) to 275/245 and any variation in between. I guess the 996 is less in need of such adjustment. By the way, you mention camber...with stock C4S suspension, there isn't much I can do, is there? As for the 996 w/PSE vs. e46 m3, 996 PSE note is 10 times better. I had an aftermarket exhaust on the M3 and it was improved, but the car still sounded like crap compared to 996.

There is some good reading about increasing tire widths here .

M3 Owner, Viken has pointed to a useful discussion. I'll add another consideration, if you change the tire width without changing to a wider rim you won't change much of anything except the looks and adding weight. If you look at the tire rack web site you'll see that they are careful to spec the rim width they use when they give the tire's cross section. Putting a wider tire on will cause the side-wall to bulge more and the extra rubber won't really be touching the road. You've probably observed that Porsche Wheels and Tires are matched to have nearly vertical side-walls. That way the maximum amount of rubber makes contact. Sometimes it helps to imagine this in reverse, think of putting a 155 tire on an 8.5 inch wide rim. The tire would be bent into a cone shape with very little rubber on the road. The reverse is also true. As to horror stories of understeer and oversteer, I think you'll find the C4S handles nicely right out of the box. To go fast, remind yourself that the rear engine car wants a different technique. Usually called slow-in, fast out. With the weight in the rear, a 911 can outbrake a front engined car (slow in). For the same reason a 911 can accelerate earlier and harder than an equivalent front engine car. As a skilled driver, you adapt to the characteristics of the car. As a general rule a 911 loves tigher corners whereas a front engine car has the edge in smooth sweepers. Fortunately most tracks have a mix of both. You may find yourself going slower than the M3 in certain corners and much faster in others. Part of the charm of a 911. Enjoy!

Thanks for the insight Bob. Its funny, it just occured to me that I met you at the extremely rainy NE-PCA event at Mont Tremblant this past July 12-13. I was asking you about your GT2 (like everyone else)... But anyway, if it is the case that the stock sizes are best, then that makes life simple. Its also good that Michelin makes PSC's in those sizes. Now, if I could just figure out how to get some more camber with stock suspension... I don't want to be eating up tires on track any more than necessary, but I also want to keep stock suspension (at least for now)...