tire fitment question for 5.5 x 15 steelie wheelies

[obrut]

hi all

i've picked up four 5.5 x 15 steel wheels for my 911 hotrod project.

i've found a local guy who can redo the rears to 7" wide (approx $100 a wheel) with new outers. i was thinking 911R 49mm offset to suit the standard 1970 narrow body. i understand that this should allow me to fit 225/50 tires with some care.

for the fronts - i was wondering if widening from 5.5 to say 6 is worth the effort/expense? 205's seem to fit ok on a 6. will a 5.5 take a 205/50 or 205/55 tire happily (i.e. without excessive bulging)? does anyone have any pics of such a wheel/tire combo?

or should i just do them all to 7" wide - with regular offset for the front pair?

[304065]

The short answer is it depends on the tire you are using-- the recommended rim size drives the width.

That being said, for a 71 "first flares" body you should be using a 225 up front as well. The increase in frontal area (drag) is more than offset by the handling balance and better braking, and it's nice to be able to rotate the tires to any corner. This is what I use on my race '71 (with 34mm offset)

[naparsei]

John,
Just more my edification, what do you mean by "first flares"? Do you mean the very modest factory increase?

Would these be the correct offsets:
6x15 fronts @ 34mm
7x15 rears @ 49mm

could this setup be run at Euro ride height with no body modifications (on the aforementioned '71)?

[304065]

By "First flares" I mean the 69- LWB flare as opposed to the slab-sided SWB.

Every wheel and tire fitment on every car is different. The only answer is, try it and find out. What may clear on one car may tear the fender lip and blister the paint on another, due to variables such as:

whether the fenders have been rolled
torsion bars
ride height
spacers
wheel offset
tread width
cross sectional width
driving style and
the pecuilarities of the 30-year-old, hand-built car, which may have been wrecked over the years

So all I can tell you is what worked for me-- which is Boxster 16x7 with a 40 ET and a 6mm spacer from H&R, with 23/31's, custom bilsteins and the fender lips rolled with as much negative camber front and rear that you can get without slotting (rules-limited), using a 225/50/16 Hoosier R6.

For example, a 205/50/15 Hoosier R6 lists a recommended rim width of 5.5-7.5", and the measured rim was a 6.5. The more width the better, in that case, because the sidewall angularity will create weird handling. You want the sidewall to be nearly vertical.

That being said, the 7R 49mm and 6 36mm with no wider than a 205 because of the sidewall angularity are a good place to begin.

[kenikh]

I really prefer 205/55 tires up front for steering feel. Grip isn't everything on cars as light as early 911s. I run 205/55s on 15x7 wheels up front, even though I could run 225s. Is it worth the expense to widen the fronts? I'd buy the 205/55s, fit them to the 5.5s and see if I liked them. You can always have the work done later.