18 by 8.5 fitment

[kdrkmstp]

Will 18 by 8.5 with +45 offset fit in the rear???
I've already rolled the fenders and currently
runny 18 by 8 with +45 offset. Let me know.
Thanks.

 

[wret]

Depends on your tire size. Since you want to use 8.5 inch wheels I would assume you will choose at least 235 width tires. In this case I would say they wouldn't fit. 38-40mm offset is about right for 235's.

 

[jtmcinder]

A 235 that is about 1-2% smaller than stock (in diameter) will fit on a +45mm wheel without hitting the vertical link. So, doing the math, we find that you want a 235/35/18. These can be found at WalMart, I'm sure.

- Jtoby

 

[kdrkmstp]

okay...i'm kinda lost.
what is the vertical link and
your saying that it'll fit if i use 35
instead of 40...???
thanks

 

[jtmcinder]

You have a 2G, right? If so, you have double-wishbone suspension front and rear (or, if you wish, SALA, with wishbone uppers and two lower links). In any case, there's a large vertical piece in the rear that wraps around and over the tire. This is what I call Scylla. (Charybdis is the fender lip. Not that I expect that Bullfinch's is a popular book on this board.)

Because you don't want to stress your wheel bearing any more than necessary, you want the tire as close to the vertical link as possible without actually rubbing on it. So I always look for the highest offset that will keep the tire off the link.

Next, note that the link wraps around and over the tire. As it passes the corner of the tire, it's at about a 45-degree angle. This means that smaller tires (in terms of diameter) can be farther to the inside. For example, a 245/40/17 Kumho MX works on a +40mm offset, but a 245/45/17 MX will not. The latter is the same width (both overall and at the tread), but it's almost 2% taller and will hit the vertical link.

It's the same sort of think that would make a 235/35/18 fit on a +45mm wheel, while a 235/40/18 will probably rub. Also, If you're going to raise the rotational inertia of your wheels by going to 18s, you might as well shrink the tires to get some of the acceleration back.

- Jtoby

ps. I think everyone should be proud of me for not going off on how silly 18" wheels are in the first place ... at least until now

 

[kdrkmstp]

Why is 18 silly???

 

[FiReBReTHa]

Show use.

exspensive to buy for street, exspensive to maintain. etc.