New Tires, going 255 up front?
 

Hi, I have a C2S with Sport Techno Wheels, so my rears are 305 width from the factory and I will stay with that width. I am curious if folks have gone 255 up front with improved performance?

I am looking at going Pilot 4S as replacements to my tired P-Zeros.

Any feedback on this or the 4S tire would be greatly appreciated.

Definitely do it. I'm running the 255/305 Pilot Sport 4S on my C4S w Sport Technos. It should've come with 255s in the front from factory, looks much more correct. 245 fitment is very stretched for Sport Technos, you can see that for yourself once you remove the wheel. 255-305 circumference also a bit closer. Car is very balanced, slightly more comfortable, great front grip turning in.

Wish I had read this thread...mine is at the dealer getting 245 and 305 P4S installed. Oh well! Will report once I get the car back.

Cheers,
NF.

I have a Targa 4S with Sport Technos and just slipped on some new MPS4S's last week. I went with the recommended 245's in the front. I too was coming from some tired PZero's. After about 300 miles so far, I really love the new tires....really smooth, sticky, comparatively quiet with excellent wet handling as well.

Been running 255/305's PSS now for 15K miles. No problems

Are you guys, uh, lacking front-end grip in street driving? Yeah, you're not. This car does a 7:38 at the Nurburgring on 245's. Pretty sure you'll be fine on your morning commute with the same sized tires.

Well, you could put 285's on the back and save money too....;)

When ur upgrading from P Zero's, UPGRADE.

My front end grip comment was in reference to track driving.

Having said that, I was having all kinds of grip issues w my old PZeros. They just don't age well. My fronts, only two years old with plenty of tread had quite a bit of dry rot, rears didn't do so well either. Especially in wet, losing traction all over the place.

With regards to 245 vs 255, it's really more relevant if you have Sport Technos. They're 9 and 11.5 inches wide front and back, while the regular Carrera wheels are 8.5 & 11. It just makes natural sense for the fitment to go from 245f 295r to 255f 305r, as opposed to 245-305 for no reason.

Just removing and looking at your Sport Techno fronts w 245s from above would demonstrate how stretched it is. I don't care what Ring laptime it runs, I'm not running stretched fitment at track, when I'm driving.

Obviously you should put whatever tires you want on your car. But a 245 fits fine on a 9" rim (as does a 255), just as there is nothing "wrong" with 245/305 vs 245/295 tire sizes. The same 911 chassis, for example, was fitted with tire sizes over the years from 185/215 ('73RS) up to 205/225 (3.2 Carreras, which also could be ordered with 15" Fuchs in 195/215).

My point is simply that you don't have to overthink this. You're not a good enough driver that you're being held back by 245/295's vs 255/305's (I've been driving on the track for over a decade and certainly am not good enough). And anyone actually that fast wouldn't be using street tires on the track in the first place.

That said....the rim width range on the 245's is 8-9.5" and on the 305's its 10.5-11.5", so the Sport Technos are in the mid range on both.

I'm a bit more visual when it comes to tire fitment. Sidewall on the 245 on 9 inch wide wheel didn't look straight to me. YMMV

Yep, nothing right or wrong. Just preference.

As little skill as I might have, I do like the way 255 handles better. Car understeers less. Turns in better. Again, fully subjective. I don't run the Porsche indicated staggered tire pressure either. To each his own. Anyone could try both and choose. That's what I did.

I don't think you need to be "held back" by them to do such minimal upgrades. Having said that - it's my only car at the moment, with one set of wheels, so I cannot responsibly run R-comp tires on it, otherwise I'd love to run Cup2s, even though I'm def not that fast. Ideally I'd love to switch to 19s and run dedicated track tires - be slow running R-comp or Hoosiers. Not going to wait 10 years to upgrade a tire from 245 to 255 or running slicks or what have you. Who knows whether I'll be able to own the car or run on track for that long. I'm doing this strictly for fun and we live today.

I wouldn't discourage people from exploring w gear. Really nothing THAT special about constraining yourself to OEM specs. Try, see what works for you.

Best thing you can do at the track in a 991 is turn off all nannies you can -- it's amazing the extent to which they cover up driver mistakes. To such an extent that guys are getting promoted into advanced groups who've only driven the modern cars and have never really learned car control (how could they, the computer does it for you). Then they're in Black and going very fast and wreck, because at some point you screw up enough that the computer can't save you.

Let me ask another, more important question about increasing front tire size.....all modern high performance cars have a bunch of parameters regarding wheel speed, assumed level of grip (coefficient of friction) etc. That help the stability control, ABS, and traction control do their respective jobs.

If the diameter of the front tire is slightly smaller than the rear due to the narrower width, then don't you need to maintain the diameter difference between front and rear, so that the ABS and traction control intervene at the correct time and in the correct amount?

With other cars I've owned, you would notice if you didn't maintain this difference. I'm all for reducing understeer, but perhaps messing with the factory stagger is not the smartest way to go.

Thoughts?