17 inch tire sizes question

[Canada Kev]

I am installing 17" tires on my 911. I seem to be having some clearance issues due to width, mainly on one side of the front with 225/45s. Would the half inch less diameter of the 215/45 cause a problem? I am using Dunlop Direzzas mounted on an 8" wide wheel and could really use that half inch less width of the 215s. I can roll the fender a bit more, but I suspect it won't make up all the space I require.

[Canada Kev]

I guess I should be a bit more clear. I now have 225/45-17. According to Tire Rack, they are 25" diameter and 8.9" wide on a 7.5 wide wheel. The 215/45-17 is 26.4 in diameter and 8.4" section width on a 7" wheel. Will the smaller diameter cause any issues? Will the width really be half an inch less on the same 8 inch wide wheel? Any little bit of width reduction will help me here, I think. Thanks.

[gduke2010]

215/45*17" is what I have on my 1985 and no rub. The previous owner had put new 225/45's on the car and i had to change them because they rubbed. the rears are 255/40's and I wouldn't recommend going bigger than that. The oil line from the tank on the right rear is close to the tire.

gary

[gduke2010]

I think my wheel diameter is 8". The wheels are 17' Turbo Twists.

[Canada Kev]

Yeah, the rear 255s are fine. Funny that the one side is fine on the front, but the other is REAL close. Hit a bump with the wheel turned a bit and bugger up the fender kind of close. Hell, a bump with the wheels straight would rub.

[sig_a]

What you would benefit from is smaller diameter Fuchs wheels as in 15 or 16 inch diameter and 7 inch width in front and 8 inch width in rear. ET front 23.3 mm and ET rear 10.6 mm. Simple reason you are having trouble fitting a 17 x 8 225 45 is that size is not designed to fit on your car. A 215 40 or 215 45 will fit but is a poor compromise. Anything larger would require fender roll and perhaps more.

[Canada Kev]

I have a set of 16" wheels with acceptable offsets and widths - turbo 7s and 9s - which fit fine, although the front is a little tight on that same side. The wheels/tires I am trying to fit are Zuffenhaus 17s which should be OK and designed to fit these cars. I have no idea of their offset. Regardless, I will likely have to roll the fender to get some clearance, but it still may be close.

Why would the 215/45 be a poor compromise?

[sig_a]

I went thru this with my 1987 marine blue 911 where 17x8 fikse mounted Nitto nt01 225 45 rubbed on the inside of driver wheel. Fender lip on driver side also cut/ruined tire at outside driver side. I switched out to 215 x 40 nitto nto1 and the performance isn't nearly as good.

If you have 16's 7 & 9 wide think about this for better handling and less cost. (Shouldn't need to fold back fender lip, either. Although much here depends on suspension, alignment, ride height, camber)

Toyo R888

front: 16 x 7: 225/45 at 23.8 inches diameter (this size provides same tread width as 215 45 17 at about 3/4 inches less diameter)

rear: 16 x 9: 245/45 at 24.4 inches diameter

[WIL84911]

Folding the lip using a baseball bat seemed to have fix the issue for me (running 225/45/17 x 7.5 inch fronts).

[911st]

Have you set your front camber to max. This can add almost 1/4" depending on you current setting.

[JeremyD]

I had 235's on my cabriolet with the 17" Zuffenhaus fuchs (8's and 9's)

In fact I even tried 275's on the rear. Stock bodied 1987.

You need more camber.

and remember you can go with a little shorter tire. (like 225/40/17)

Tire size calculator

(check out tire specifications closely - they can differ greatly depending on tire manufacturer - 215/45/17 from Toyo might not be the exact dimensions of a 215/45/17 from Dunlop)

[Canada Kev]

How much does changing the camber affect handling or anything else? I know changing suspension settings usually requires an alignment, but can the camber be adjusted the same amount on both sides with no ill effects?

Rolling my fenders will likely be this weekend's project. I didn't want to do this because of the risk in damaging the paint where the fender lip folds over. A bit of heat and a gentle touch will reduce this probability, I hope.

Right now, I have Dunlop Direzza Star specs mounted.

[JeremyD]

Roll em up Kevin - a broom stick and a hair dryer set on high are your friends...

[Canada Kev]

I have a real heat gun. It gets much hotter than a dryer. Plus, I don't have a hair dryer. My coiffe doesn't require it.

I also did some searching, and discovered that adjusting camber also will mess with toe settings so an alignment is required.

[m110]

Interesting, I have Zuffenhaus wheels but run Size 7.5 and 9 X 17 with DUNLOP DIREZZA SPORT Z1 STAR SPEC in 225/45-ZR17 and 255/40-ZR17.

No rubbing whatsoever. Jeff posted the offset of all the sets at one point but I can't find it now. They are, however, completely optimized for a 3.2 as I spoke extensively about it with him.

Sounds like rolling the fender and some camber might do it.

[Canada Kev]

OK, a bit of an update is in order, I think.

True to my nature of not leaving things alone when I get in the "WTF is going on?" mood, I scratched my head, had a beer and thunk a little.

"Well, that side fits nice, and this one is WAY too tight. What would fix it? Roll the fenders. Ok, that's likely required and is probably a good thing to do, even if to avoid possible issues down the road... Can't do much about it right now, though. What else...? Camber. Hmmm, I wonder what they're at right now...?"

So I take an aluminium straight edge and my handy dandy iPhone with the free and somewhat helpful level application and make a ball park measurement against the tire. Damn, I'm already almost 1.3 - 1.5 degrees. Wait a minute. That's POSITIVE one and a half degrees!! Well, no friggin wonder it's tight. Hopefully it'll adjust out...

So now all I have to do is find a decent alignment shop in this not all that very Porsche friendly city. Time to call someone in the PCA maybe, unless someone here chimes in with a suggestion. Anyone?