Normy

Well, looks like I need new tires. Again.

-I've driven my '85 S2 5 Speed about 40,000 miles in the four years that I've owned it. In that time, I've put two sets of tires on....which makes three sets if you consider that there was a set of new-but-cheesy Kelly 225/50-16's on the four corners when I bought it.

The latest set, Bridgestone RE730's, have lasted about 15,000 miles...barely. The fronts are now down to the wear indicators, and the rears appear to not be too far behind. What's more, there is at least one tire that out of balance.

The RE730's are pretty decent tires overall. I never had a problem with them- no pulling, no nails picked up...only a slight tendency to flat spot when I leave the car in the garage for a few weeks while I'm out flying. I know why they wore out prematurely- I changed out the steering rack earlier this spring, and aligned the car by sight, with the idea that I would immediately have it aligned professionally. Only...the alignement place refused to attempt to align the car due to bad lower ball joints. I knew they were bad, but didn't have time to change them right then, so I let it go while I went bouncing around the world. And then the girlfriend came to Florida for a few weeks...blah blah blah.

Funny thing: My "eyeball alignment" wasn't all that bad- on the highway, I could take my hands off the wheel for nearly half a mile before the car started to gently wander over the centerline.

Sitting on my kitchen table right now are a pair of new ball joints [it's great being a bachelor: car parts on the kitchen table and a motorcycle in the living room!], which are going to go on the car when I get back home from Belgium. Then the ride height will be restored to normal...so that I can install the new tires and expect to get a few miles out of them, since incorrect ride height eats tires quick. I'll align the thing professionally only after the tires go on.

WELL, I've been researching this and have come to the conclusion that 225/45-17's will work fine on my 7.5 inch 993 wheels. Right now, I'm running 275/40-17's on the rear, and love the way they look. However, the Devek website says something about the ratio of wheel width to tire section width not being less than 0.85 [wheel should not be narrower than 85% of tire width], and this concerns me a bit because my rear wheel is 9 inches. To save you the math, this works out to about 0.83, or 83%...

I haven't had any problems, but then again I don't autocross my car either. I had the car on the twisty roads of Western North Carolina a few weeks ago, and it seemed to handle great, but then again I'm not a professional driver, I haven't had any racer's training, and I probably wouldn't notice it if my car was oversteering slightly due to sidewall tuck-in anyway.

So I don't know whether to downsize my rear tires to 255/40-17 or stay with the cool-looking 275's. I'm also trying to pick between Bridgestone RE750's [a new tire], or Yokohama ES100's- both tires have nice high treadwear numbers.

ANY thoughts?

Normy!
'85 S2 5 Speed
-Gettin' fat on waffles!

Shane

Go with the Yokohomas!

hacker-pschorr

I have 255/40-17's on my '81. I don't have a picture of the rear profile to show how the width is. I'll try and take one to give you an idea. I think these look fine. Especially when parked next to a 944 or 928 with stock wheels, these look really nice.
I was always wondering if I could run wider as well. My wheels are 10" wide, so I'm guessing from your research I could run 275/40-17's on my car. I've got RE-730's as well.

sweanders

I would go for 255 mm wide tires on 9' rims.

Gretch

N, I am running the 255/40 on 17 in rims (rear) and would like to get a wider tire if I could do it. I second the emotion about the Yoks, They have been very good to me. My decision to go to a wider tire would be based on cost differential and any empiracle evidence of wear or handling problems with the wider tires.

It sounds like you are saying the latter is a non issue, and I am happy to hear this.

I have an interest in understanding the effect of the wiessach axel setup on handeling, and especially so in concert with bumpijng up against the .85 that Devek recommends.

Do you have any insight on wear pattern with the 275's? I would guess that the middle will wear out sooner, especially at higher presures like 44 lbs. What pressure do you run in the 275's?

Sab

I have 275's on my 9' 996 rims and they look and feel great.
cheers,
Sab.

Ed Ruiz

Over time, I've had them both. I prefer the more secure feel (less side to side movement) of the 255 on a 9" rim. Moreover, the speedometer and the odometer read true, whereas with the 275 tires, they tend to read below the real speed and distance (not much, but maybe just enough to get you in trouble). :^(

Anyway, the GTS series were shod with 225 and 255 tires. Since my wheels are GTS type, the tires look perfect on them, and that's just fine by me. YMMV.

John Struthers

Normy,
You have room for the 275's without rolling the fender lips? On a 17' wheel?

I'm sure they look good in any case but do you need them? Unless the roads have changed a lot since I blew thru Fla. the curves were not in abundance. Why a more expensive tire with a track that will undoubtably have you wandering from side to side in those miserable truck wheel paths.
The look, I like!
The freakin' wandering has you 'steering' your sHARk all the time. Trying to track straight on a straight road making inputs all the time goes beyond irritating...
Your call. Let us know how the swap turns out after a few thousand miles.

Randy V

THe 275 tires are recommended to be mounted on a wheel 9" to 11" wide.

See the Tire Rack chart:

<a href="http://www.tirerack.com/tires/Spec.jsp?make=Bridgestone&model=Potenza+RE750" target="_blank">http://www.tirerack.com/tires/Spec.jsp?make=Bridgestone&model=Potenza+RE750</a>

I've got RE750 275's on 8.5" wide wheels (17 inch wheels).

Bridgestone no longer makes the RE730 in 275 size for 17" wheels.

Brent 89-GT

Since you only street drive the car, I don't see the 275's on a 9" wheel as a problem. You have a pretty small front tire so the chances of experiencing oversteer based on the wider tire on a narrower rim are nil IMO. If you like the look and the feel, indulge yourself <img border="0" title="" alt="[Wink]" src="wink.gif" />

A 928 set at proper ride hieght and properly aligned does not track poorly in my experience. I have 255/40-17's in front and 275/40-17's in back. I have 1.5* negative camber dialed in and zero toe. I had the tech run more caster than stock, 4-5* I think. I also run the Bilstien / Eibach shocks and springs, so the car is , uh hem, firm. My car tracks extremely well, and I have plenty of DEEP truck ruts in my area.

Again, if you like the look and feel, I do not see you violating any major unwritten 928 laws here. I would also say that 14k miles on performance tires is not too bad. I don't expect to get that many on my Kumho MX's.

Mark

I think that the 'tracking' in the truck ruts is more a function of tire type than tire width.

My YOKES do NOT track at all. My old Eagle GS-C's did...as did the Pirelli p-zeros that came on my new wheels. AND - the P-zeros were 205 on the fronts!

Normy

Gretch-

I'm running 3.0 bar/44 PSI, the most the RE730's allow. I still have more wear on the edges than the center! My wear patterns might not be a good study- I have incorrect front ride height and my own alignment job. For what it is worth, these wide tires definitely reduce the tendency for my car to spin its tires from a standing start, the reason I did this to begin with. The car does have a tendency to "tramline", or follow ruts in the pavement. This is a very gentle tendency, not something that discourages me from buying new 275's.

John- Yeah, the 275's fit fine with no rubbing. I have the 993 wheels [not sure of the offset], but when I bought this combo, I had to remove a pair of 21 mm factory Porsche spacers that apparently came with the car. Right now, I have about 1/4 inch of room between the tire and the lip, with no evidence of rubbing. Yes, the car does gently move about, but I can still take my hands off the wheel, even with my own alignment job, for quite a ways.

Brent- I guess your front wheels have a different offset. I have always wondered about fatter tires on the front, but have shied away because I'm worried about rubbing. I doubt I could get away with anything wider than 225 mm on my fronts with my 993 wheels...what have you done to prevent this from happening? 255 on the front sounds hot!

N!

John Struthers

Anyone know for sure why the front track on the 928's is noticeably wider on the front than the rear -at least on the early model's-?
I can't see any difference on the 928 vs the 928 S
even with the 80 or so HP advantage.
Just curious, not throwing any curves.

Th Dude

I'm running 255's on my cup 2 wheels with the rear spacers left ON. They fill out the wheel well right to the edge.
Wide stance.
Minimal flex.

Jim bailey - 928 International

John front track is about 61 inches and rear is just over 60 ...so you are seeing less than 1/2 inch on one side . It is a visual illusion that the rear wheels are tucked in .