On a wheel that has a +42 offset as I understand it you need a spacer for this wheel to fit on a 240Z. Question is would the spacer need to be a -42?

A + offset means the wheel where it attaches to the car is further from the car where as a - offset it is closer. Right?

I think my spacers are 40 mm thick to mount my 40mm offset wheels.

Hi texasz,

Here's a page from TireRacks web site that'll explain what an offset is.:classic:

http://www.tirerack.com/wheels/tech/offset.htm

Then my quesiton is, where is the stock mounting point on my 240Z? Is it at zero offset inside the wheel housing, or (+) some milimeters?

I'm buying the adapters from Modern Motorsports, but they are very vague about how thick the adapter is. When I asked, I got this response:

"The adaptors suitable for wheels ranging from 36 to 40mm offset as described (range of 0.15", not much) are of one geometry only. So if your's fit the recommended offsets and widths you'll be just fine with our typical adaptors. Custom adaptors we can do separately but sounds like you're fine with our typical adaptors."

When I pressed the issue they admited that the adapters are 1.1", which converts to 27.94 millimeters. How is this going to fit a 40mm offset rim?

On a side note, why are they using standard measurements when offset is traditionally in metric? Especially for a Japanese built car. I'm pretty sure these guys are Canadian, and their whole country standardized on the metric system. I'm boggled. :cross-eye

Thougt it would be helpful to add a link to the product I'm talking about. Z to Honda Wheel Adaptors

For 14 and 15 by 7 inch wide wheel on a 240Z, offset of 0 to +15mm is best fitment. that means the mounting plane (that rests against the hub surface) is dead center in the middle of the wheel (for a 0 offset) or 15mm outboard (moving the wheel center inboard). The Hondas, and most FWD cars, use a 35~40 offset. If you tried to use this wheel on the Z, the back of the tire would be hard against the strut tower. To change a +35mm wheel to 0 offset, you would need a spacer 35mm thick. If you put a 35mm spacer on a +40 wheel, it would be effectivly a +15 wheel when you finished.

By the way, on 16 and over wheels, a +15 offset is optimal as a 0 will rub the outer fenders on bumps. So if you bought some 17X7 +40 4X100 SSR's, the spacer offered by Modern Motorsports would be just about perfect.

Originally posted by Victor Laury

........ If you put a 35mm spacer or a +40 wheel, it would be effectivly a +15 wheel when you finished.

? ? ? I'm lost here.

I think I understand. I was planning on on a set of 15 x 6.5 +40 4X100 Nippon Racing F2's (12 pound alloy wheel). So, if I follow the logic, the offest would be +12.06MM with the adaptor. I might consider getting a 7" rim, to fill out the wheel wells with a slightly wider tire.

Thanks for the help Victor.

Originally posted by Bambikiller240

? ? ? I'm lost here.

I misspelt. My bad. it was suppose to read

"If you put a 35mm spacer on a +40 wheel, it would be effectivly a +15 wheel when you finished."

Instead of "or"

Originally posted by Victor Laury

I misspelt. My bad. it was suppose to read

"If you put a 35mm spacer on a +40 wheel, it would be effectivly a +15 wheel when you finished."

Instead of "or"

Yes, I figured that part out. What confuses me is :

"To change a +35mm wheel to 0 offset, you would need a spacer 35mm thick." I think I understand it this far. 35mm offset wheel, 35mm spacer to put back in ZERO offset place.

BUT Then, "If you put a 35mm spacer on a +40 wheel, it would be effectivly a +15 wheel when you finished."

Following the first example, I'd have thought the wheel would be effectively a +5 wheel. 40 - 35 = 5 ? This is where I get lost.

Well you Can't expect me to actually do rithmatic, do you? You know I aint got 40 fingers and toes! I know some. The adds and the takes-a-ways and even some of the gizindas (4 gizinda 8, 2 times). I'd know more but, in school, Elle-May Clampet was always wisperin in my ear bout the swimin hole. Makes it hard fer a man to think bout anything except multiplication.