Lawrence Franz

Hey Guys ... please help me here ...

I picked up a beauitful OEM set 0f 17 x 8's and 17 x 11's - 911 rims or boxter not sure which ... but they look just fantastic to make my 84 Light Gold 928 pop

need to know how wide of tire this 928 will take

Im lookin at 275-40-17's for the rear ( will I get away with rolling the lips )
and 255-40-17's on the front
some one can help me with the max tire size .. please let me know if you can
advise is good
Lawrence from Sunny So Cal

James Bailey

Everything depends on the offset of the wheels......everything !

Rob Edwards

If they're OEM Porsche wheels there should be some numbers embossed on the rims next to the valve stem hole. What are those numbers?

Lawrence Franz

I just had the rear tires removed this afternoon and I just now walked out to the shop to measure the rear rims .. so they are actually 8.5 inch wide
and that other number next to the stem says 50

and of course it's all about the offsets ... gotcha
some one with experience may have the ground roots experience ... you can see by the attached pics which wheels Im running

MjRocket

I run 11" Carrera III wheels with 295's and a 5mm spacer with no issues, my fenders are rolled.

But as stated above Offsets are the determining factor.

SeanR

Wow, flash from the past. That was my car circa 2006 the day I got her home.

Speedtoys

..and tyre section width.

295 means nothing.

255s can..in the SAME tyre model, be as wide as a 295.

mark kibort

put a ruler to the wheels and tell me the backspacing. fronts and back and ill tell you exactly what size tire you can run and how much fender rolling or spacer you need.

back spacing is just the mounting surface to the inside edge of the rim.

Mark

PS.... if that rear rim for example, is a 8" backspacing, you can run 305s in the rear and use some minimal fender rolling with a baseball bat, just to crush the insided fender lip. 255s up front, but with a 55 offset, it might be a problem.

mark kibort

Not really...in fact.......never

MjRocket

Agreed!

Speedtoys

typo on my part, I meant 285, I dont have 295s mounted.

Here's my data...and my problem

Bridgestone A050A's

Size: 285/35/19

• On my 11" wheels, the section width of these is 10.6", with a tread width of 9.1".
• On the 10" wheels I am moving to, these are 10.2/9.1 respectively.
• On the 255/40/18s on my 10" wheel, they will be 10.5/9.1 respectively.

1. Narrower wheel.
2. Far 'narrower' tire.

A big phat .1" narrower overall, where it counts, in the fender well. The smallest unit of measure available is the difference.


Section width has HUGE meaning in this discussion.



So..how is this never true? Is it the torque, or the horsepower?

MjRocket

He was speaking "Never true" for a 255...Big diffrence.

mark kibort

thank you!

its never true that a 295 can be the same width as a 255.

thats a fact and you might have an issue with facts, as in Torque vs HP...." hp is made up from torque", for which i think you know. now, a 285? hmmm maybe..... like to see a picture of that one, but 295, sorry, never.
I can attest, some slicks and DOTs can have a wide range of widths for the same section width. the widest range ive seen is my 305s from pirelli slicks, are the same width as some 285s. thats about as far as ive seen the width mm spec fall down.

no one has played that game more closely than i have... ive have a business card clearance in the rear for years...... taking the 335s on an 11" rim , knocks down to about .5" over all. however, its still much fater than the 305 or 315 but close to the 315 by a .25". i posted pics a while back of all sorts of combos on and off rims. toyos, hoosiers,, all on 11" rims and fronts on 10" rims.