Needsdecaf

So my neighbor just got a 997.2 Turbo S with aftermarket wheels. I noticed he has 245/35-19 and 325/30-19's so I visited some of the past threads on the subject. I'm not looking to change my wheels and the stock Turbo S wheels are 8.5 and 11. So I went looking at some data.

Remind me again, what tires came standard on this car? Mine has PS2's but I know they are replacements. Did it come with PS2's or PZeros? Or both?

In any event, the standard fitment is 235/35-19 and 295/30-19 in the snow, or 305/30-19 summer. Interesting. So the diff isn't so sensitive that it can't handle different tire diameters front and rear. And then I looked up and noticed that none of the combos match exactly! It's always a little more or less than 3% off, the rears being slightly larger. So I can't see the combo of 245/35-19 and 325/30-19 hurting anything. Take a look. The number in the graph is revolutions per mile. Data taken from Tire Rack.



I’ll be looking to get new tires in the spring, and am definitely going with PS4S. Would definitely like to up size after seeing my neighbor’s setup.

Needsdecaf

So no opinions on this? Anyone running 245/35 and 325/30 on the stock 19's? Seemed like all the other posts from the other threads where people were running this combo were on aftermarket wheels.

Akkord29

I am running 245/305 with no issues on my .2 stock wheels. If the 325 are within the threshold then should be a problem.

IMI A

I run this size on stock wheels too but hardly ever have them on the car as prefer the BBS.

tonupbklyn

I'm about to get a set of PS4S in a few weeks, and in anticipation of the install had been researching the hell out of this topic for some time.

I've recently concluded, based on many findings (posted and commented on in this forum), that 245/325 not only fit but work perfectly fine on stock 19x8.5 and 19x11 wheels... as well as the F/R ratio is no concern.

also cuz i have no plans on moving away from my stock suspension and CL spyders, these sizes appear to fill up the wells very nicely.

see here photos of others who have gone the same way.

Needsdecaf

Those photos won't up-size for me so can't really see what it looks like.

Hope you get them soon so I can see how they look!

Thanks.

JoeFromPA

You should be able to fit thornbirds if you are looking for the ultimate in grip.

All kidding aside, could you speak to your goals here with different tire sizes?

Wider tires front or rear will increase tire noise and tend to increase tramlining/feelings of instability on grooved pavement. They'll be heavier, usually. Tires that are wider and taller (i.e. 325/30 vs. 305/30) will act as a gear reducer, effectively making your final drive ratio taller and reducing the accelerative force a bit.

I've seen people go with meaningfully larger tires (wider and a bit taller) and wind up with ~5-8 pounds more unsprung, rotating, worst-polar-moment-of-interia-ever mass PER CORNER PLUS a 3-4% taller effective final drive ratio and hate the feeling it has on acceleration and braking. I doubt you're looking at that scenario, but you should simply consider what the goals are and if the minor trade-offs are worth it.

P.s. Just met with first AIA

nzskater

That’s always been my thought as well. Why add weight/mass for little real world benefit.

To anyone that has gone wider, what are the benefits you’ve noticed?

wcarson

Very wise words. The larger tire size looks better, although it's not a drastic difference IMO. But when I went from stock sizes to the larger tire sizes (ie, 325 in rear, 245 front), I could certainly feel the difference. The bottom line is that the car is palpably less sharp with the larger heavier tires. If you are not a performance junky like I am, it probably doesn't matter. But when my 325/245 wear out, I'm going back to the smaller stock sizes.

jayzbird

Remember that the tires will push out on both sides, so you’ve got inner fender clearance to consider as well. Not just in your garage but under load as the tire stretches, especially on track. With 5 lugs you can add spacers if necessary, but there is no such option with CLs.

Needsdecaf

Looks. But also grip. I’m not sure if something is wrong with my car, or my tires suck, but man my car can struggle with straight line traction at times. Launch control is ridiculous, skewing sideways and struggling for grip.

JoeFromPA

I've gone for "the look" as well. In that case, pick a tire that looks badass in it's size and sidewall and tread and hues as closely to your current height as possible. Watch weights too.

On your straight line traction: I''ll probably cause an argument but wider tires DO NOT INCREASE straight line traction nor do they increase contact patch for straight line traction purposes. So if your issues are straight line traction, a wider tire will not itself solve it.

IMI A

I find it helps reduce understeer. If I could run 305 with a 245 or 255 I would. Anyone that doesn't find it helps understeer is not driving their cars fast enough to notice the difference but even in slow corners massive difference. On road no difference.

I haven't tried Cup 2 in stock sizes though so on track but cars natural stance weight distribution and awd made mine understeer out of the box. Then over steer once I'd sorted understeer! Doesnt do this on the 245/325 set up

harlycharly

I have the Michelin PS4S in 245/30/20 and 325/25/20 on HRE wheels with no clearance issues.