Joined: Wed Dec 21 2005, 07:34AM
Location: indiana
Posts: 791
BigBlockMopar wrote ...
When it comes to tight fitting tire-situations like this, would you really just copy some backspace number from a forum, or just measure it very carefully on the car itself?
This! Copying someone else without verifying everything yourself could lead to trouble. Trouble that you might not notice right away, either, it might take the right combination of load, braking, bodyroll and a pothole to put an ugly rub on a sidewall (or worse).
When I went thru the 'fat-tire' project on my 68 Fury I did *a lot* of measuring. Not only the car, but rearend housings also. I was going to use 15x8 Ramcharger rims (4-4.25" BS) and either 275/60 or 295/50 tires, so I knew the tires were going to wind up at the wheellips. So I anticipated to re-lo the springs and put a slightly-narrower B-body under it. I had a buddy with probably 20 loose 8.75 housings, which made it all possible.
Here's what I learned: Rearend housings can vary up to 1/4" or more, from the published data and also from identical ones from same cars (relating to end of housing and/or perch location). I wouldn't have believed this if I hadn't seen it myself. Maybe they had multiple welding jigs back in the day that weren't the same, yet were within tolerance? Rearend housings are different lengths side-side vs the pinion centerline (normal) and also to housing end and perch, and so the axle flange might not end up in the same location in the wheelwell on each side, so check *both* sides of the car.
Now you're not changing rearends, but I mention all that as reason why you must not casually take internet setups, and must measure both sides of your car.
So - I swapped rearends and moved my springs to throw an extra 1" of rim depth because that's the look I wanted. And it worked out really well. I don't think I'd ever do that again. When I do it next time, I'll put 255/60s on a set of standard 15x7 rims (4-4.25 BS) and call it a day. This combo has fit on every C I've tried, wether fusey or slab, and skirts or not.
Look thru recent posts of mine, this topic has come up recently and I believe I typed a book in one of them. There are a few more details I've posted about inner wheelwell shape, fenderskirt hooks, and some other stuff I've forgotten.
Oh - I test-fit the 295/50 on that 15x8 on several cars (an AMC Spirit, a Lincoln Mark VII, and my Fury) and it was downright goofy-looking on all of them. Looked bad on the Fury even though most of it was covered, as it still put the back of the car higher than a cat's ass. I wish I took a pic of it.
Joined: Sat Apr 04 2009, 10:33PM
Location: washington
Posts: 163
So 15x8's with 4.5" back space or 15x7 with 4" backspace? Will the 15x8 work up front without rubbing? Or should i do a staggered setup? 7's up front, 8's in the rear?
Joined: Sat Apr 04 2009, 10:33PM
Location: washington
Posts: 163
I am leaning towards 285/70R15 on 15x8" 4.25" BS rims for the rear, but i am worried about the fit. No one has them local so I can go check them out, I have to order them.
Joined: Wed Dec 21 2005, 07:34AM
Location: indiana
Posts: 791
I was being facetious on that tire height to make sure you realize that's a really tall tire, and at 70 series will have a *lot* of sidewall showing. I didn't realize that a 285 tire existed, so I googled some pics, and I have a hard time envisioning that looking good on a car.
It's not my car, so it's not my call, but as you have to order the tires first, I said that as a suggestion to make sure you are pleased with the results before you buy some tires you probably can't return.
You also need to watch your width closely, for a tire that seems to fit snug can actually be wide enough to pop your fenderskirt latch open if the sidewall flexes going around a turn.