so here is my dilemma, i have a new set of Nitto Motivo's in 255/45R18 that i am planning on using on my car, got a great deal on them. but i really want some fat rubber in the rear, a 295/45 most likely, so i will either buy a set now or just use the 255's on the wider wheel til i eat them up. the MAIN dilemme is back spacing. i understand nearest to 0 degree, but i will at some point in the future, unknown when, bu converting this car to C5 brakes. it currently has front factory discs and rear drums. will this hurt my setup when i switch to discs?

 

I can't comment on the disc brake issue, but when you say "nearest to 0 degree" i'm confused. I put MT 12x30x15 on my '72 with 8 1/2" wide rims.
I bought 4 1/2" backspace rims and they are fine. Could have perhaps been 4 3/4 or 5" but they would have been a custom.
A 10" rim would be about 5 1/4 - 5 1/2" back space.

George

 

I assume you mean "near 0 offset", which is in inches, not degrees. A rough conversion of offset to backspace for zero offset is half the rim width plus about 1/2", or about 4.5" for an 8" wheel and 5.5" for a 10" wheel. The actual backspace will vary +/- a quarter inch or so depending on the contour of the wheel lip on that particular wheel.

 

Great website for calculating offsets, backspacing, etc...

http://www.rimsntires.com/specspro.jsp

 

Here's all the details on my wheels:

The new wheels with the B-body spindles on front and 13" rotors on front with 12" rotors on rear are:

Front Tires/rims- NewGen500 18x8 rims (5.25” BS) w/Nitto 555 255/45/18s
Rear Tires/rims- NewGen500 18x10 rims (6.0” BS) w/Nitto 555r 305/45/18s

My old rims with stock spindles and stock rotors were:

18x8 ARTT2 Front rims – 4.5 BS - 255/45/18 Nitto
18x10 ARTT2 Rear rims – 5.5 BS 305/45/18 Nitto

As you can see the B-body spindles and bigger rotors pushed everything out in the front by .75" and the 12" rotors is the rear pushed everything out .5" (thus the smaller BS required to push the wheel back in).

So it's important if someone is going to get similar sizes they adjust accordingly for the spindle and rotor used. Also the fender well lips still had to be rolled to prevent rubbing on the outside and the inner fender had to be "massaged" a little on one side with a BFH.

Hope this helps.

Pics of both sets of wheels here: http://highperformanceolds.com/phpbb...hp?f=29&t=2882


-Joe

 

If its enough mass in the center of the rim,its possible to take off a little to get the rim goes more in. But a machine need to do this with a dealer or something

 

I have C5 brakes on my car. Be careful with wheel selection, when I had 17's I needed a spacer to prevent the spokes from hitting the face of the caliper. My current 18's have a curved spoke and no spacer needed. The fact that I went from 17's to 18's had nothing to do with clearing the brakes, I just wanted better tire selection and sizing options in 18" size.

You need to find out the backspacing or offset on the wheels you have now, and we can help more.

255's on a 10" wide wheel will look goofy, IMO.