Still confused about wheel widths with offset trailing arms
Thread Starter
Instructor
Joined: Feb 2001
Posts: 163
Likes: 0
From: Milan MI USA
Still confused about wheel widths with offset trailing arms
I know we've talked this to death but ,I'm still confused.Here's my question .I have a 68 with offset trailing arms.And i would like to run a wider tire (for HP reasons)I want to run 15" rims (rallys) Can i use a 10" width and still stay in the wheel well. I have enough problems with michigan roads (pot holes and gravel that i don'tr want to rip my outer fender lips off.Or should i stay with the 8" width.Any help would be appreciated .(remember 68-69 had no rear fender rock guard.) Thanks terry
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: Still confused about wheel widths with offset trailing arms (Terrys69coupe)
Terry, I have a '72 with stock arms and 17x9.5 '92 vette rims on it, all around...running 275/50/17 Nitto in back and 255/50/17 Nitto in front now....
I miss the t-arm by about 3/8 inch on inside sidewall....I moved the Ebrake cable, obviously....gained easy 3/4 inch by doing that as offsets remained the same....
now I am told shark bodies sit sometimes a bit askew on the frames...I don't personally beleive that, as mine is square up....
but the previous presence of wide flares on my car is told by previous owners...there is a LOT of filler material in my fenders does NOT feel like the hollowed out casting on other cars.....
but for the life of me, I can't see the flares I have NOW stick out much if any further than a '78 or so....
I think there is more room than many guys allow there is...but I dunno why...
I do think 10 inch rims are about the limit though...even with offset arms. as the sway bar touches, then the spring...
in front, I rub the sway bar sometimes, and or the chassis... but not hard or alot...
GENE
I miss the t-arm by about 3/8 inch on inside sidewall....I moved the Ebrake cable, obviously....gained easy 3/4 inch by doing that as offsets remained the same....
now I am told shark bodies sit sometimes a bit askew on the frames...I don't personally beleive that, as mine is square up....
but the previous presence of wide flares on my car is told by previous owners...there is a LOT of filler material in my fenders does NOT feel like the hollowed out casting on other cars.....
but for the life of me, I can't see the flares I have NOW stick out much if any further than a '78 or so....
I think there is more room than many guys allow there is...but I dunno why...
I do think 10 inch rims are about the limit though...even with offset arms. as the sway bar touches, then the spring...
in front, I rub the sway bar sometimes, and or the chassis... but not hard or alot...
GENE
Thread Starter
Instructor
Joined: Feb 2001
Posts: 163
Likes: 0
From: Milan MI USA
Re: Still confused about wheel widths with offset trailing arms (mrvette)
Hi Gene what offset or backspacing are on your rims in the back and how is your ride quality with the 17" rims VS stock 15". Thanks for the reply terry
Burning Brakes
Joined: Jan 2001
Posts: 1,004
Likes: 16
From: Gainesville, Florida
Re: Still confused about wheel widths with offset trailing arms (Terrys69coupe)
Offsets give approx. 2" clearance from the arm at the widest section of the tire using stock backspacing (4") & a 255/60X15 tire. See thread:
http://forums.corvetteforum.com/zerothread?id=244231
With that in mind, a 10" rim w/5" backspacing will move the tire in 1" & out 1" due to the same neutral backspacing with the 2" wider rim. Accounting for the sidewall width at its widest point, you should still have about .5" inner clearance. On the outer, with the same 4" backspacing, the sidewall is approx. 1" inside the outer wheelwell edge so the 5" backspacing on the 10" wheel should put the sidewall about even with the wheelwell.
Mark
http://forums.corvetteforum.com/zerothread?id=244231
With that in mind, a 10" rim w/5" backspacing will move the tire in 1" & out 1" due to the same neutral backspacing with the 2" wider rim. Accounting for the sidewall width at its widest point, you should still have about .5" inner clearance. On the outer, with the same 4" backspacing, the sidewall is approx. 1" inside the outer wheelwell edge so the 5" backspacing on the 10" wheel should put the sidewall about even with the wheelwell.
Mark
Thread Starter
Instructor
Joined: Feb 2001
Posts: 163
Likes: 0
From: Milan MI USA
Re: Still confused about wheel widths with offset trailing arms (mdsmith)
Thanks mark i think that puts it into prospective for me .I'll order my 10" wide rims with 5"backspacing tommorrow .Thanks again guys just want to be sure .Don't want it to look like a hoopty when I'm done.Just fast and clean
Le Mans Master
Joined: Nov 2000
Posts: 5,210
Likes: 104
From: Fort Worth TX
St. Jude Donor '06
Father & Son St. Jude Donor '09
Re: Still confused about wheel widths with offset trailing arms (Terrys69coupe)
Can't you measure the current clearance that you have? Locate what's closest to your sidewall, frame, swaybar, spring etc. Then you can add that to the backspacing of your wheels minus 1/4" - 1/2" to get the maximum backspace you can run so you can minimze pushing the wheel and tire out too far.
Also, can you return what you order? If not, maybe you should order one at a time. When I ordered my 15x8's, I told the guy I was concerned about clearing the caliper, so send me one. He said he'd guarantee it would clear in writing so I ordered them all. Just a thought.
You might IM Lasse. I think he has 15x13's with a 5.5" backspace and offset arms. That could help confirm if 5.5" is do-able or not.
Also, can you return what you order? If not, maybe you should order one at a time. When I ordered my 15x8's, I told the guy I was concerned about clearing the caliper, so send me one. He said he'd guarantee it would clear in writing so I ordered them all. Just a thought.
You might IM Lasse. I think he has 15x13's with a 5.5" backspace and offset arms. That could help confirm if 5.5" is do-able or not.
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