930 tire question

sscates · sscates's Garage

Hey guys,
Need your help. I've got an 82' 930 with the original Fuchs (7 & 8). Two questions. The original equipment is 205, 55's up front and 225, 50's in the rear. I would like to bigger, but not huge. 225 in front and 255 in the rear is what I was thinking. Should I go to 50 series in the front or stick with 55. Also, I was going to go with the Potenza SO-3's. Somebody told me that Michelins were a lot better tire and softer to boot. Your opinions are appreciated. I have tried in the past with no luck to upload a pic of my car with no luck. I'll try again.
Steve

Sarah · Sarah's Garage

Hi Steve,

I saw you had a 930 also so I thought i'd "bump" this for you.

Good luck getting the answer to your question. S~

IROC · IROC's Garage

Just since no one else has responded...

Really you're kinda pushing it to put 225s on the 7s and 255s on the 8s. I mean, you can do it, but the tires are a bit wide for those wheels. A 245/45-16 fits really nicely on an 8 inch wheel. The 225/50-16 fits OK on the 7s (heck that's what the factory put on the 7s in the rear of Carreras), so I guess I would say go for the 225/50-16s and 245/45-16s.

Or buy some 9s for the rear.... :>)

Mike

ted · ted's Garage

I have some new 225/50/16 and 255/50/16 Sumitomo tires for sale if interested, I'm near by in San Diego.
Here's a pic on my #59, these tires have 300 miles on them and have never been raced. I decided to put some Victorracers on these rims instead. email me wfo2m8o@yahoo.com

Bill Verburg · Bill Verburg's Garage

225/50 7 245/45 x16 on 7 & 8 is doable, but not ideal. the rims are on the narrow side for those tires. 255/50x16 is getting kinda tall and doesn't relly match a 225/50 very well. you can do it but again the match isn't ideal.

In 16s you would want ~+25mm o/s 8" wheel on the front and ~+15mm o/s 9" wheel on the back, w/ your stock 930 spacers. 225/50 & 245/45

IROC · IROC's Garage

Quote:

Originally posted by Bill Verburg
225/50 7 245/45 x16 on 7 & 8 is doable, but not ideal. the rims are on the narrow side for those tires.

Bill,

I've heard this repeatedly (the 245 being a bit wide on an 8) but this is exactly what I have on the front of my car and they do not appear too wide at all? Maybe some brands of tires vary enough to make this a hit or miss thing? I've run the old BFG R1s and now A032s on the 8s and they don't appear too wide at all.

Maybe I'll post a picture later on when I get home just for the phun of it...

Mike

Bill Verburg · Bill Verburg's Garage

It's not an appearance thing it's pure design. 245/45 was designed by the tire engineers for a minimum rim size(in most cases) of 7.5" and a maximum rim size(in most cases) of 9"

The tire will work ok anywhere in that design rim range. To get maximum benefit the widest or at least close to widest design rim possible is desired. The wider the rim the more the section width is stretched and the shorter the sidewall becomes as a result. A tire that is nominally 245/45x16 on an 8" rim actually is stretched into a 260/34x16 when stretched over a 9" rim. The tread width stays the same of course but the handling characteristics become those of the 260/34 rather than a 245/45. When the tire is placed on a narrower rim the opposite takes place. These are not theoretical #s I have seen and measured this effect many times over the years. The above #s are from the last set of 245/45x16 RE 71s that I used on my own car(shaved to half depth of course).

IROC · IROC's Garage

Thanks for the info, Bill.

Mike

BlkBird · 11-03-2003, 04:22 PM

BTW. Potenza's are an excellent value for money in my opinion. They are great in the rain and easy on the pocketbook.

sscates · sscates's Garage

Hey there,
Thanks for the conversation. Along with your ideas, this is what I've decided. I stuck with the original size on the front (205/55/16) and went with (245/45/16) on the back. From what I've been told, going to a smaller series on the front would just make for a stiffer ride and more pulling. Also, wider on the front would just make the car harder to drive at slow speed. I guess I shouldn't be able to out drive the 205's. I went with the 245/45's on the back since that is what they put on the 86 930's. I believe the car is the same as mine, as far as the suspension is concerned. I went with the Bridgestone S-03's for the same reason as above. Thanks for tires for sale post in SD.
Steve