[968Oz]

HI ALL

I am buying 17 x 7 and 17 x 9 Cup 2 wheels and am considering what tires to get.

I think the "standard" sizes were 205/50 and 255/40.

Has anyone experience or advice on other tire sizes, particularly with a 968? For example how about 225/45s on the front?

I use the car on weekends and intend to start on the track next year without getting too serious about it.

Any advice on brands and types would be greatly appreciated too!

Thanks

Ian

Partial Post: Please Login or Register to read the full post.

[rob76turbo]

I am running the same size Cup II's. For the track, I am running Toyo R888 - 255 / 40 (Rear) and 225 / 45 (front). I like this combination.

Partial Post: Please Login or Register to read the full post.

[Cloud9...68]

[quote name='rob76turbo' post='64746' date='Dec 27 2008, 10:42 PM']I am running the same size Cup II's. For the track, I am running Toyo R888 - 255 / 40 (Rear) and 225 / 45 (front). I like this combination.[/quote]

According to the owners manual, the specified 17" wheel/tire sizes are 225/45ZR 17 on 7.5" rims in the front, and 255/40 ZR 17 on 9" rims in the back.



I recently purchased a set of Sumitomo HTRZ III's for less than $100 each from Discount, and I am utterly flabberghasted at the sheer excellence of these tires. I previously had a set of Goodyear GS-D3's, which were the #1 rated summer performance tire in a fairly recent comparison test by Car & Driver, and the Sumitomo's absolutely blow the Goodyears away, at 40% lower cost. I track my car at least once a week, and these tires keep getting better as they wear. They grip like crazy, and at the same time are utterly forgiving. I can't recommend them strongly enough.

Partial Post: Please Login or Register to read the full post.

[xrad]

Cloud 9 : how is the sidewall flex in the turns?? I had Pilot Sports from Mich and sidewalls were very rigid and have never found a similar feel in other brands.

Partial Post: Please Login or Register to read the full post.

[flash]

wow - that is the first time i ever heard somebody say that about the pilot - i find the michelin to be one of the softest sidewalls out there - that's one of the reasons that they ride so smoothly - perhaps you had them over-inflated?



if you thought the michelin was stiff, you should try the bridgestone S0-3- ugh - great traction, but stiff as a board



as for the original question, a 225 on the front will create some wallowing on a 7 - not a good thing for track, but won't be an issues on the street - plenty of guys doing it



as to the wheels, i assume you meant 993 Cup wheels, and that was a misnomer - check the offsets to make sure they fit properly - there are a few different ones out there

Partial Post: Please Login or Register to read the full post.

[xrad]

Really? I went from PS's to Goodyear and my BMW felt very loose in turns at all speeds... I need to find a good Summer tire with possible track use for teh 968.

Partial Post: Please Login or Register to read the full post.

[flash]

well, feeling loose and sidewall stiffness are two different things - a hard tread compound can feel loose, but have a soft sidewall - same goes for a stiff sidewall and a soft compound - there isn't really a direct correlation between sidewall and loose - it's more the compound and pressure



the tell-tale about sidewall stiffness is "snap back" - when you come out of a turn, and transfer weight abruptly, if you feel a bounce left to right, it was probably sidewall rebound



if it's just "loose" it's likely either tread compound or inflation



michelins tend to need a couple of pounds more air than most other tires - if you had the others at the same pressures as the michelins, dropping a couple of pounds might have resolved your problem



last i heard, the best gripping tire out there right now is the yokohama advan neova ad07 - pricey though - the sumitomo is not far behind it, and a LOT less expensive - unless you are pushing the envelope, i am not all that sure anyone will ever be able to tell the difference - i am probably going to swap to the sumitomo on the M3 very soon - may do it on the 968 too (still on the fence on that car for other reasons)

Partial Post: Please Login or Register to read the full post.

[968Oz]

[quote name='flash' post='64770' date='Dec 28 2008, 09:52 AM']as for the original question, a 225 on the front will create some wallowing on a 7 - not a good thing for track, but won't be an issues on the street - plenty of guys doing it



as to the wheels, i assume you meant 993 Cup wheels, and that was a misnomer - check the offsets to make sure they fit properly - there are a few different ones out there[/quote]



The wheels are ET55 front and rear. From my research on this forum they should be OK on a 968 right?

Partial Post: Please Login or Register to read the full post.

[xrad]

by loose, I mean 'snap back or not at all' I could throw the Pilot Sports into a hard turn and the car followed ONLY rarely with some slide. Wore those out in two years and next set was not nearly as good, to the point of me having to change my driving habits.



I will look into Summitomo's. hope they have a 275 18

Partial Post: Please Login or Register to read the full post.

[flash]

968Oz - they will fit



xrad - yeah - sounds like compound or pressure, not sidewall that caused your problem - sidewall is more of a wiggle - go out and push sideways on the side of the car (make sure you don't dent the car doing it) - watch the sidewall flex - see how it bounces back - that will always happen, but to a larger degree - it's the return bounce that is the problem with a soft sidewall, not the initial flex



whatever you do, don't get the conti - those things are a mess - i can't get them to work well on the M3 no matter what i do, even though they are the specced tire for the car - noisy, slippery at the limits, and LOUSY wet traction - i've got to get those off the car before she wraps it around a tree

Partial Post: Please Login or Register to read the full post.

[xrad]

Flash: it was definately sidewall weakness and weak tread compound (with the addition of brand new tread height) because even on 10-15mph sharp turns, felt like the front was snowplowing and not going where I wanted it to. It was fine the day before with the Pilot's. Moot point, I got rid of the car and the tires with it. If I had to , I would have replaced them with another set of the Pilot Sports. They had great grip on dry pavement and super stable. But I had the M suspension package, too, which might have been too stiff for the other brand.



Still searching for a good 275 18 tire for the 968.

Partial Post: Please Login or Register to read the full post.

[flash]

again, unless you were extremely under-inflated, sidewall flex has little to nothing to do with anything except snap back coming OUT of a turn when the weight starts to transfer back - it acts like a spring - when the sidewall is stiff, it resists that compression, and inherently the corresponding release



snowplowing, slipping, or anything like that, would be tread compound, tread pattern, tire temp, or inflation



the pilots are a great tire under all but the most aggressive situations - they do require a bit more inflation maintenance than a lot of other tires though - how much needs to be gauged by a tire temp reading - they are a lot like the contis in that regard - as an example, we took the M3 out to the track - i dropped the pressure in the tires for what i expected to be the typical 4 lb bump when hot - it turned out that i had to drop the temps another couple of pounds up front to keep it from plowing - it was amazing how much of a difference it made - she went from sliding all over the place, to tucking in quite nicely - made for a much better day for ayn, and for me too on the drive home through a very fun canyon - i had not really warmed up to the car until then - i am still stunned at how different it felt - it went from skittish and twitchy to planted and tight



i still like the 968 better though



i'm not saying that the sumitomos won't be a great tire, or even a better choice, but if you liked the pilots (except for the mentioned issue), and cost is no object, i might consider getting them again and play with the pressures more



here's the drawback of a soft sidewall tire: while absorbing bumps and such better, and all that, a good pothole and you can bash a rim on a super low profile tire, especially if you have a fair amount of negative camber (ask me how i know) - this is exactly what has prevented me from changing tires yet - i need to design a camber kit to get rid of the negative camber in the rear (which i don't need anyway now that i have the monster sway bars) - once i've done that, then i can go to a softer tire and gain back some civility that i lost with the 18s



it's that or i go back to 17s

Partial Post: Please Login or Register to read the full post.