I noticed a lot of people are shopping for new rims just in the last few days, both on the forum and on the BBS. I've been shopping too, except I don't plan on buying for a little while yet.

I'm becoming more than a little concerned about this because of the offset ranges people are looking at (mostly in the 38-45mm offset range). This range worries me because I've tried to collect useful (and hopefully reliable) info about what hits and what fits.

First of all, here's the simplest explaination of offset: http://www.whalentire.com/faqs.cfm#offset Offset is measured in relation to the center of the wheel, not any of the edges of the wheel like "backspacing". As offset gets larger(+) the rim moves inward. So say you want to fit a 235/45 size tire on 17" rims. If the rims have the same offset, that tire should fit the same under the fender whether the rim be 7" or 8" in width.

Okay, now I've gathered just a few, key bits of info from various people in both forums, namely Jeff, Mr.Rose, DanNY, and a few other people who own big rims with fat tires.
1) The 17x8 Mustang rim you hear about has 30mm offset (supported by an ultra detailed Mustang site I found).
2) The Mustang rim with the recommended 235/45 tire fits with about/less than a finger width of clearance to the strut, and not too much room to clear the fenders in the rear.
3) A 38mm offset rim may rub (on the strut I suppose) depending on the tire. Some tires have a "rim protector bead" on the side.

Using these bits of info I concluded with a "safe" offset range of only 30mm to 35mm.

I know Mr.Rose has done a lot of terrific measuring and hard work in the Konig rims thread, but I want to get this out in the open and make SURE we're all certain about this offset thingy and come to a consensus - before someone lays out some hard cash on a very expensive mod. Granted, all my info is SECOND HAND (I have stock rims) so I'm sticking my neck out a little here. Anyone could be mistaken - including myself - but I feel that given the above info, a rim with over 38mm offset might have tire rub.

(Of course this assumes the tires will be 235 width. Narrower 215 or 205 width tires may be okay with 38mm+ offset, but I haven't studied this.)

Again this is all based on information provided by other people, but I think this should be discussed (and FAQed) for the sake of all current and future wheel buyers.

So, 30-35mm offset? Or 30-45mm offset?

[me digs hole]

 

me hides behing Bman.