Jim912928:
The wheel to tire ratio for a 265mm on a 9" rim is 0.86, which is just within the safe margin for fitment. YMMV.

Jeff F:
Tire pressure is yet another variable cussed and discused as if it were a religious argument. Each person and car drives differently. The roads I drive on may be very different from those on which you drive, etc. Over the years, I've come to the conclusion that 38 to 40 psi all around seems to work best for me. Without a doubt - YMMV.

When I get an alignment, it's done with the tires inflated at 40 psi, the tank full, and 150# of dead weight in the driver's seat. Also, the car is within the factory recommended ride height range.

Lastly, my computations of the odometer and speedometer are based on the original wheel and tire sizes. Going +1 or +2 often throws off the readings. Since I also participate in rallies, it's important for me to know the exact time and distance traveled. Again - YMMV.

 

Ed...thanks, I appreciate your knowledge!

 

My $.02 ...

'Stones NOT Yok's. Why? FL rains require the advanced UNI-T adhesion.

Second: Go with V rated tires not Z since you will (probably) not need the extra speed capability and apparently want the extra mileage.

 

Let's try not to get too hung up on the "ratio" of 85 % . The 85 % rim width to tire tread width was adopted as a convention by the tire manufactures so they could then measure the tire cross section (widest part of the sidewalls)in a standardized manner and had little to do with safety . Tires with an aspect ratios higher than 50 % use a 70 % ration . When Yokohama says their tire will mount to a 7-9 inch rim , it will . However the handling will be much better using wide rims with " narrow " tires .

 

You know, I don't have any of the problems that you guys have. When the guy at the gas station sold me those Atlas tires, he said "You're car is going to float over bumps like a barge..." and he was right. I love that vague feeling, it's a real highway cruiser now !

 

Narrow tires...mmm...
Jim
Do you think a 255 tire is too narrow for a 10 inch wide rim? I´m moving to 18 inch rims. To mantain the same tire diameter I had with the 17 inch rims, its seems I only have two choices 285/30/18 or 255/35/18. Based on the comments here, I would better install the 255, if possible (the guys at the tire shop say it is within acceptable widths).

 

275s on 9" rims are fine. Ive raced tested that combo for a couple of seasons!. for street, i wouldnt give it a second thought.
MK

 

the 285 x 30 x 18 gives you a 25 inch diameter tire . that 285 mm width is fine on a 10 inch rim it does only give you a 85.5 MM "rubber band" 3 inch side wall between the rim and the road so be very careful . Hit a three inch deep pothole and you may buy a rim or two .

 

Hi Jim!

Sorry if my post was not clear. I´m not an english native speaker. :-)
I plan to install the 255. Do you think it´s too narrow for the 10 inch rim? The tire guy says its in the limit but acceptable.
The current worn tires installed(rears) on the 18´s I have just bougt are 285s. You are right. So little rubber its a bit scary. I want to install narrower (285 is too tigth, even on my GTS) and taller tires.

Regards,

-Vince

 

Your GTS has wheel spacers which could be removed to allow you to run the wider tires , a 285 x 35 is taller .

 

Hey Normy,
I also do my own alignment, and also had my dirtbike on it's stand in my livingroom for years. So now maybe you'll trust me when I say to run away from the Yoko's. I had gs-c's and put a pair of av-100's on the rear. They were so bad, I had to put them on the front to keep the car from wagging like a fish. Inflation was 40 psi. I'll never get another pair. I want responsiveness, and they definitely aren't. They are low in price, though.

 

Run the 275's. The larger you can fit, the better. 275's are fine on a 9" wheel.

I currently run Pilot Sports, 285/40-17 front and 315/35-17 rear. I'll probably go to A032R's next.

Enjoy...

 

Gregg- I got a decent deal on the Yoko AVS ES-100's, so I went with these. About 1500 miles so far, and certainly no complaints!

-As to the "home brew" alignment: After replacing one rim, resetting the ride height to the correct level at all corners, and installing the new wheels...I immediately took the car, which seemed to drive straight as an arrow...to the Porsche dealer for an alignment. It drives different now- more stable for sure, and the dealer mechanic told me that my settings were way off! Oh well, I wanted to replace the rubber anyway....

N!
'85 S2 5 Speed

 

>Your GTS has wheel spacers which could be removed to allow you to run the wider tires , a 285 x 35 is taller .

Yes, Jim, I removed the spacers but even with them out its a tigth fit (993 offsets). Besides that, I dont like too wide tires. I prefer the 255 but wonder if its too narrow for the 10 inch rim?

Regards,

-Vince