'69 Rear Tire Sizes - Team Camaro Tech
Wheels & Tires What fits what?

 
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post #1 of 15 (permalink) Old Jul 1st, 00, 10:11 AM Thread Starter
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The question of rear tire size keeps coming up with different answers all over the map. I finally crawled under my car a few minutes ago and did some measuring.

The available space (not considering the shock and mount intrusion) from the inside of the lip to the inner wheelhouse on my car is right at 11-3/4". Assuming that my car is "normal and stock" with these dimensions - and allow a little clearance on each side and that says that the maximum tire you can run inside the wheelwell without rubbing is an 11" sidewall width which generally leaves you with a 10" tread width.

Anybody disagree or have different measurements?

On my car I have 8" American Torque Thrust II rims in the back and 255/45/17" BFG Comp T/A tires which gives me 9" tread width and a 10" sidewall width. I have about 1/2" clearance to the the lip and about 1-1/2" inside.

However, because my car is lowered 2" I now only have 3/4" between the shock bracket and the edge of the wheel. Unless I relocate my shocks inside the springs (a definite possibility) I can't go any wider.

If I do move the shocks - the next step in TT2 wheels I believe is 9-1/2" which would fit with the proper b/s - maybe 5-1/4 or 5-1/2"?? . My total inside available space is just about 11-3/4" inches - so I could reasonably go to an 11" sidewall tire and still not rub with the right backspacing. You could probably squeeze in a little more but I'm not up for clearance problems. The BFG site says their 275/40/17 Comp T/A has an 11" section width.

So - computing all that means that the biggest setup I can squeeze inside the wheelwells of my lowered ride are 9-1/2" wheels with 5-1/2" BS and BFG Comp T/As @ 275/40/17" and that's if I move the shocks.

Any ideas - thoughts - angles I've missed? Has anyone moved their shocks? Anyone running these sizes on a lowered car?

------------------
Scott
'69 400SB, Richmond 5-speed; '99 HD Road King Classic
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post #2 of 15 (permalink) Old Jul 1st, 00, 05:43 PM
 
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Rockymountain,
your math looks pretty good, I came up with the same numbers except for the total width lip to lip on mine is 11 1/2. but on the rest I came up with the same answer 9-1/2" rim, 5-1/2 backspacing, and to get the best fit with a 275. (some say more (295) will fit but I will believe it when I see it!)

Currently I am running BFG 235/60-14 (8"wheel, 10" sidewall width, crappy 7" tread) and there is no room on the outside but about 1-1/2" to use on the inside.

I have talked to a couple people that have built these to the max before and say a 5-3/4 backspace with 10" rim, and tires differ between manufacturer to actual size, so have the tireshop test fit everything before you buy!

my .02

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post #3 of 15 (permalink) Old Jul 1st, 00, 06:29 PM
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I have been looking into this question alot lately and 5.5" of backspacing in the rear with a 275/40 seems to be the biggest tire that will fit. I too considered moving the shock inboard, but when I went to perform the operation I notice that the item limiting the maximum clearance is not the shock but the inner fender. The top of the shock is mounted betweent the inner fender and the frame, but the shock is at an angle so the shock is closer to the wheel at the bottom, but on a 16" or bigger wheel the shock will not come close to the tire, if it does for some reason then I intended to just make new lower shock mount, by cutting the mount off the lower sping perch and welding it so the shock is closer to the spring thus making the shock more straight up and down, do you see where I'm coming from? I just don't see, at least not on my car, why moving the spring in would privide anymore clearance.

------------------
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post #4 of 15 (permalink) Old Jul 2nd, 00, 05:58 AM Thread Starter
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Mark - The problem with the shock comes when you lower the car. I think if you used re-arched springs you would be OK but I used 2" aluminum blocks. This drops the shock mount down to the interference point even with a 17" rim.

I agree that you should be able to cut and move just the lower mount so it's more inboard and I may try that first.

I think moving the spring in has to be part of a larger re-work where you also do some mini-tubbing and move that inner fenderwell over a bit. I think it also requires either relocation of the gas tank or a custom smaller tank. That's way too much cutting for me - I'd be happy just to get to the 275's. (although the 295's do look nice ....)

Thanks!

------------------
Scott
'69 400SB, Richmond 5-speed; '99 HD Road King Classic
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post #5 of 15 (permalink) Old Jul 2nd, 00, 06:41 AM
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I was just going to make a lower spring mount out of a flate piece of steel and then welding a tab directly off of the plate, not down and out like the factory one, just like traction bars do it, that should elimintate the problem even if lowered. As for mini-tubing I'm still thinking about doing this, but the more I think about it the more work I realize it is. If you have it, check out the January 99 issue of chevy Hi-performance, page 26, now this car has some meats. It has been mini-tubed and has 315-35 rears and 275-40 front. I don't see how those front tirs fit without rubbing everywhere, and it sits good too. What do you think?
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post #6 of 15 (permalink) Old Jul 2nd, 00, 08:04 AM
 
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Rockymtnracer~ I`m running 17x9.5 TT2`s with 5.5 back spacing with 275/40/17 on my `69. Its a tight fit! The car is lowered only a inch. The problem you might run into is that your car is lowered alittle more. The inner side walls of the tire will rub the upper part of the inner well. I had to stiffen the rear up with a one inch sway bar.(did not want to) But, the car is just a weekend cruizer. I had to do no modifications to the fenders. I sill have about 3/4 inch from the inner wells.and about a 1/4 in from the outer fender. I think if you roll the fender lip with a baseball bat, you may get alittle more room on the outersides. Make sure you measure correctly before buying those rims!

[This message has been edited by 69 Ragtop (edited 07-02-2000).]
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post #7 of 15 (permalink) Old Jul 2nd, 00, 10:51 AM Thread Starter
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Ragtop -

thanks for the info. So - cruising around on Hawaii in a Camaro convertible! Sounds like rough duty!

Do you have any pictures of the car and tires? Maybe with some sweet Hawaiian babes posing near the car (just to provide some perspective)?

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Scott
'69 400SB, Richmond 5-speed; '99 HD Road King Classic
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post #8 of 15 (permalink) Old Jul 18th, 00, 08:43 PM
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Check out page 40,41 of Chevy High Performance, August 00 issue. This 69 is lowered 1" and is running 17x9.5 rears and 17x7 front TT2's. He's got 285/40zr17 rear and 225/45zr17 front. It looks pretty tight but it looks good.


[This message has been edited by golopogos (edited 07-18-2000).]
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post #9 of 15 (permalink) Old Jul 19th, 00, 05:50 AM Thread Starter
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I talked to the guy with the CHP black Camaro. He's running custom backspacing up in the 6" range and some thin spacers to get the tire best centered. He also said there was some work done to the inner wheelhouse and the lip is seriously rolled. He claims they do fit with "hardly" any rubbing.

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Scott
'69 400SB, Richmond 5-speed; '99 HD Road King Classic
www.geocities.com/sdenning1
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post #10 of 15 (permalink) Old Jul 21st, 00, 07:51 PM
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Thanks for the info! It sounds like a little more mork than I'd like to do to my 69. The 275's sound like a little better setup. Thanks again! Golopogos
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post #11 of 15 (permalink) Old Jul 24th, 00, 06:04 AM
 
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I measured my wheel wells on my 67 this past weekend. The narrowest part was 11.5". I also have a template of a 275/40/17 tire and put it in the wheel well. It only had about a 1/4" of clearance. It looks like it would rub if you hit any bumps. I also measured from the axle flange to the inner wheel housing and got 6.5" on both sides. It looks like a 9" wheel with 5.5 backspacing would be ok. Does anyone know if a 17x9 will work on the front with a 245/45/17.

Kent Wissman
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post #12 of 15 (permalink) Old Jul 24th, 00, 06:16 AM
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Kent, if you only want a 245 tire then you'd be better off with a 8" wheel, also most of the good wheel manufactures don't offer 9" wheels but 9.5".

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68 468 700R4, and here it is;
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post #13 of 15 (permalink) Old Jul 24th, 00, 09:43 AM Thread Starter
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Kent - I'm with Mark - a 9" to 9-1/2" wheel is too big for either a 245 tire or the front end. I run a 7" wheel with a 245/45/17 front tire.

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Scott
'69 400SB, Richmond 5-speed; '99 HD Road King Classic
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post #14 of 15 (permalink) Old Jul 24th, 00, 09:53 AM
 
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Mark,
The reason that I was asking about a 17x9 for the front was I like the wheels that they are putting on the 2000 camaro ss. I looked at the picture of your car on the web and was wondering what kind of wheels you were using that were the 16x7 and 16x8. I am having a hard time finding a 16 or 17 inch wheel that I like and reasonably priced that has the proper bolt pattern and spacing. I would like to have 17x7 front and 17x8 rear with 245/45 and 265 or 275/40 17 rear.

Kent
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post #15 of 15 (permalink) Old Jul 24th, 00, 10:34 AM
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The 16" wheels are torque thrust II, I put them on this spring but next spring I'm going to 17" wheels (probably Budnik's Famosas, but something new might come out before than that I like, it just seems like to many cars jumped on the torque thrust bandwagon). Here's my plan: rear 275/40 on a 9.5" with 5.5" backspacing and for the front I'm going with 245/45 on a 8" wheel with 4.75" of backspacing. I've done as much research on the subject as I can and unless I find out other wise those are the sizes that I think will work best and the biggest sizes. The 20" and 18" that I ran on my car for a season gave me alot of information on what fits and what doesn't, the 18" wheel was a 18x7 with 3.5" backspacing and a 235/40, it fit very well and I liked where the tire was as far as distance to the outside of the fender, but a 235 on a 7" wheel is max, so if I go with a 8 inch wheel and 1.25" more backspacing it should work out well. As for the rear it was a 20x10 with 275/35 with 4.5" backspacing, and they looked presentable but stuck out to far, so if I go with the same size 275 tire on a smaller 9.5" wheel with 1" more backspacing then the tire should sink in the fender about 1.5" and that will look great. The only problem I see is if the 5.5" backspacing is to much and the tire rubs the inner fender, if that happens then I'll just add spacers and longer wheel studs to correct this problem.

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