So I have done my research and I appear to end up in the same place each time. It looks like its going to be the Michelin PS2's. The current Pilot MXXs appears to be a decent enough tire but old technology and noisy, I want to stick with Michelin and they don't offer the PS2 ribbed (N rated) or MXXs in new rubber compound for the GTS.

I know there are many cheaper tires that are as good but from what I have read a couple $$ difference isn't worth it for me if i am going to gain noise or loose wet traction.

I know it has been discussed numerous times but if I could get feedback from those who have them on their cars, preferably 225/45/17 255/40/17 sizes I would appreciate your opinion so far. I did a search and have read some negative comments about wet traction while others say they have no issues.

The rears are on back order for 4 weeks and I might as well hear what you have to say before they come in and there is no going back.

Thanks in advance

 

Anthony, I really like my PS2's. My fronts are 245 and the rears are 255. Good dry and wet traction, the rears are wearing at higher rate than the fronts.

 

I have had the MXXs and now Pilot Sports (not PS2s) on the GT......stick with the Michelins, expensive but well worth it IMO......haven't found anything better. The MXXs were great in the dry but bad in the wet........the PS and PS2 have since solved this issue.

 

Isn't that always the case with a heavy right foot.

I would assume a 2 to 1 ratio rears to fronts for replacement on a tire like this.

I am assuming the sidewall on the 245 is a 40 vs 45? The rolling dia appears to be rather close with 24.7 vs 25 inches. What benefits do you feel you have gained with the 245's?

 

What is the widest front and rear tires that can be installed on the stock GTS Cup wheels?

 

I have Pilot Sports N1 in 18" and I like them better than S-03, and AVS Sport. The PS has the most uniform ride and they don't get flat spotted from parking as easily as other tires. Great performance both wet and dry.

 

Anthony, I think the 245 fronts are 40 aspect ration and the rears are stock 45's, but I will check tonight when I get home.

The PS2's wear well, but autocross and DE events have certainly diminshed the life of the tires. The fronts look like they will outlast the rears by 2 to 1.

I've got stock width GTS wheels and the PO had put 245's on the front, which is what I've stuck with. It seems to understeer a bit less with the bigger front tires.

 

So if they are 45's, than the overall dia would be 25.7 which is .7 inches over the 25 inch stock fronts.

I found the GTS to handle fairly well on the skid pad although you reach that point of understeer earlier than I expected. My wife and I have been using the car for a few autocross events and plan on doing more. Although I just don't fit well in the car with a helmet. (now I see why so many cherish the none sunroof cars. I fit much better in the 911 with a helmet and sunroof) I was curious if anyone had tried the 265 40 or 275 40 rear sizes in combination with the 245's up front. The rolling dia would increase to 25.3 & 25.6 respectively.

Is there any way to compensate for speedo error if you were to change to a 25.6 dia vs 25 inch dia tire?

 

That small change in diameter size will be a very small change in speedo reading - not enough to worry about.

Run the calcs here: http://www.miata.net/garage/tirecalc.html

How about my question above?

 

Anthony,
I'm currently running the 225/45 and 255/40 17" Pilot Sport 'twos' (PS2s) over 7"/9" widths on a S4. So far, they do everything the Pilot Sports do on my 16v car ( in 16" sizes) - but do so more quietly and with more comfort ( unique for an all out tire!). The SO2s they replaced were the noisiest tires I've ever used on a 928, so the contrast is dramatic.
I've used the MXX all fabric belt tires, the MXX3s, etc. As much as I liked the MXXs in the dry, the PS2s are definitely an advance: you will like them ....


Randy,
What are the rim widths - 7.5 & 9"? If so, I would stick to 225/45 fronts. A 235/40 requires a min 8" rim and a 235/45 is marginal on 7.5", plus slightly larger in diameter. Generally, a given tire will perform better when spread to the wider end of a recommended width range, especially on a steering axle. 255/40 is a good fit on 9".
Many will recommend the widest that can be squeezed on. This leaves the bead and sidewall angles compromised from the tire designers perspective - but has become religion on the street. Perhaps I was too close to the design & testing side to be objective ...

 

Thanks, Garth!

From the 928 Registry Spec page:
_______________________________________________

PORSCHE 928 GTS (1994 from VIN 0080 and all 1995)
17" Cup Style
Wheels = Front -7.5x17 / Rear - 9x17
Offset = Front - 65mm / Rear - 55mm

Tires = Front - 225/45 17 / Rear - 255/40 17

___________________________________________


So, are those the widest I can go front and back, then?

 

In a PM to me Jim Bailey says:

figure 235 front 275 rear any more and the rims are too narrow to work well. Remove the rear spacers and you can run BIG WIDE rims $$.

OK, so 235 and 275 on the Cup wheels it is. Thanks, Jim.

 

Randy -

Yup. I'm wearin' 275/40's on the rear of my car on stock rims. They look and handle very nice. I've only got about one finger-width of room left between the tire and the wheel well, even with the GTS flared rear fenders. So yeah, anything wider and I'm sure you'd need to remove the spacers.

 

Anthony,

Good choice. My car came with Toyo's, but I'm going to put Michelin's on when these wear out. I've always been a Michelin Man. Hey, they invented the radial tire, and are leading in the Formula One standings!

 

Thanks all

Looking at the Michelin Spec sheet it appears they approve the 235/45/17 on anything between 7.5 & 9 inches with an overall dia of 25.4 inches.
The 275/40 17's are approved for anything from a 9.0 to an 11.0 inch rim with an overall dia of 25.6 inches. Stock rubber being 25.0 inches overall dia.

I would have to assume that like Randy said that .6 inches in overall dia should not make a discernable difference in speedo readings. I like the idea of the wider rubber, although my tire guy feels I would be pushing it with these sizes and recommends against it. In either case they are still on back order for several weeks. I guess the big question is stay stock or go wide?