Porsche Newbie

Wondering what the best tire size is for those rims.. no rubbing allowed! Don't want to have to do anything to any fenders or anything..

stormmaster

Mine are 205/55 in front......225/55 in the rear....no issues

Driver8

Rob, my first question is what year 911 are we talking about. Secondly has the car been lowered or is it stock height? Carerra's that came with 7's and 8's from the factory had 205/55/R16 on the front and 225/50/R16 on the rear. Or you could opt for 245/45/R16 on the rears, they should fit with out a problem if the car has not been lowered.

Porsche Newbie

My bad! it's a stock height '78 SC.. thanks!!

Porsche Newbie

One other thing.. there are 205/55's on there that appear to have rubbed.. thinking 205/50's and 245/45's

racer

I agree with Driver 8's suggestions. Be aware you may be limited in sizes because there are fewer 16" tire sizes available, especially if looking for a high performance or "R" compound tire. I wouldn't recommend a set of Sears Roadhandlers either.

As an example, check out a site like tirerack.com . They have fitment guides that will work for your car.

Peter Zimmermann

Rob: 7s on the front can always present minor clearance issues, mostly when owners opt for 225s. Use the stock sizes - 205/55 front & 225/50 rear - and you should be fine. If your car is indeed stock fiddling with oversized/incorrect tires won't do anything but frustrate you. Tire Rack is an excellent source for friendly advice, but contact your local Porsche Club of America region as well. I currently run Bridgestone Potenza RE750s on my SC (lowered, corner balanced, but otherwise stock), and they're pretty good. The advantage to using original sizes is that when they're on the car it will "look right."
Pete

goldrench

Exactly what handling effects will change by dropping the fronts to a 205/50? Oversteer/understeer?
Rears will remain 245/45.

My87Targa

hmmm i run 205s on my 16x6 wheels up front and 225s on my 16x7 in the back

Peter Zimmermann

Hey guys, keep in mind that the only front wheel authorized by the factory is a 6x16, fitted with a 205/55 tire. When Porsche fitted 7s & 8s to 911 Turbos they still used the 205/55 fronts AND the 225/50 rears. When they went to a 9" rear they fitted 245/45s, the correct tire for a 9, not an 8. If you wanted 7s on the front the factory would oblige, but they were 15" diameter.

manfredhegwer

I spoke with someone (I think his name was Jason) today, who sells restored OEM 16X7,8 wheel sets on ebay. He told me that these typically come off of pre 1986 Turbos and Turbo Looks. The offsets on these wheels are the same as the offsets on the 15X7,8s. He said that with the 16" OEM 205/55s and 225/50s there is no rubbing issue. I intend to mildly lower my 85 targa to what I guess would be called european ride height. To what extent does this cause a rubbing risk? Are there any particular high performance tires that tend to run a little bit narrow for added clearance in the front?

Edward

With 205s/225s on 7s/8s you should have no rubbing issues at all at euro height on an SC-later car. Euro height is pretty mild lowering so you should have no problems even with 245s at the rear. FWIW, I'm lower than euro height and have no rubbing with 245s on my 8s. It's usually the front where 225s may rub, depending on the ride height and camber.

Edward

earlyapex

I run 225's on 16x7 inch wheels up front with no problems, but my car has -2 degrees of camber and the fender lips have been shaved off.

Peter Zimmermann

manfred: Your situation might cause slight rubbing depending on your final tire choice. I've rolled the front fender lips on a few cars to correct minor rubbing, there should be no problem with the rear regarding your proposed setup. Although Eric's setup is extreme, and you don't want those kind of camber numbers on a street-use car, you can always have your lowering/alignment specialist dial in up to half a degree negative. Be very careful who you choose to do the lowering, there are a lot of shops that do it without proper equipment, etc. Go for it!
Pete

JCP911S

Technically speaking, a wider tire yields higer ultimate cornering capability, so increasing rear and not front would cause to car to oversteer less/understeer more.

In reality, spring rates and suspension also significnatly impact oversteer/understeer as does driving style.... so generalizations are risky.

All this really comes into play at 9/10th and above.... for a street car, you really shouldn't be driving that hard IMHO, so the difference in tire size should not really be that critical.

If it were me, I'd stick with the 205 on front as they will track better and be less likely to rub. Put the 245 on back if you like the cosmetics... it won't hurt anything.