tire width question AGAIN!!!

[megavega]

the tire size you run is going to be dependant upon the rear axle width and rim offset, and your own taste as to what you think fits in the wheel wells and most importantly your ride height! I used a 2wd s10 rear axle which is 54" wide, it is 1/2" narrower then the stock vega axle is. I am running 17"x8" rear rims with 4" of backspacing with 235/45/17, and your not gonna get anymore rubber under the wheel well lips unless its jacked way up in the air, my wheel well lips ride down over the tires, pics can be seen in the project section under pro touring vega. I have not had time to update the build with new pics because of work load here but will shortly.

[NixVegaGT]

I used to know this stuff off the top of my head but I'm pretty sure the stock H axle width is 49.8" or something. I'm pretty sure your right the S10 is 54" or so:

http://dave.h-body.org/Build%20a%20Bett ... %20End.htm

So is that 49.8" number to the axle flanges? or the axle tube ends? That's what it's got to be right? If not how is it that the S10 axles are 1/16" shorter with the same center section. WHAT THE?

Link to Don's Vega Pix:

http://forums.h-body.org/viewtopic.php?t=20726&start=15

[megavega]

vega rear end is 54.5" wide at the axle flanges where wheels bolt up to, the 2wd s10 is a half inch narrower at 54"

I simply had the rear axle out on the floor and placed a carpenters square against the brake drum/axle mounting flange,the surface where your rim touches, and marked each side on the garage floor, then measured it, did same thing for both the vega and s10 rear ends, pretty easy to measure a straight line on your floor. That 49.8 measurement is to the housing end only and doesnt take into account the axle offset.

on the s10 axle swap for the newer 7.5 vega rear ends, its because of the offset on the axle, and the rearend being a half inch shorter, thats why you have to grind the lip of the brake drums slightly if they rub the backing plates.

[NixVegaGT]

Cool! Thanks man. That's what I was looking for. SO since I'm also using the S10 28-spline axles I should be 1/2" shorter too.

I foolhardily followed the FAQ reference for the 8.5" fits with 3.5" backspace and discovered NO WAY on the Vega. The early Vega for sure. That may be true for the Monzas though. I think in the end I'm going for 16x8. 245/45 16

On to the front!

[grumpy d-bone]

so nix you say no way on the 8.5x15 wheel on a 72 gt?????

[spyder_xlch]

Grumpy, don't you have a 9" rear? The width of your rear may be different. I've seen a method for calculating tire/rim size, offset, etc. I don't know where I've seen it. It may have been posted here somewhere or maybe on another site.

[grumpy d-bone]

ok how can i measure the ford 9in in my 72 gt now?
under it from flange to flange? let me know ill go out and do it now see what you guys think

[grumpy d-bone]

ok just measured mins is approx 54in from back flange to back flange thoughts on 15x8.5 rims?

[megavega]

simply place the car on jackstands placed under the rear axle itself, as low as you can, with the rear wheels off, use a carpenters square against the brakedrum/axle surface where your rims would touch it, transfer your mark to your garage floor. (I make marks next to the lines I draw on the floor like "ax" for axle, and "wwl" for wheel well) Then using some string and heavy nuts from a bolt tie the nuts to the string and hang them from the inside of the wheel well lip via a set of vise grips, transfer your mark from the nut to the ground (the string and nuts are just a plumb bob) do this the same for the inside wheel well.

Now move the car out of the way and you can now work with your marks on the floor as its a map to your actual wheel well clearance and your rear axle width. (you also can use a piece of cardboard and put the marks on that and not have to move the car if need be)
Its best to subtract 1 inch from each side of the wheel well to permit for body roll, this will keep the lips from chewing up the sidewall of the tires. I think youll find your not gonna be able to use more then a 8 inch wide rim, and your section width of the tire will need to be around 9.5" overall. You can easily see how backspacing effects the clearance both in and out, so if you know your wheel is 4 inch backspacing you can draw it out on the ground with your other measurements and know 100% accurately if it will work or not. This way when you go buy your rims, you know before you buy them if they fit or not! pretty easy.

Again, it matters the MOST as to the RIDE HEIGHT you have the car set at, if its sitting high you could use more width but it would need to stick out past the lips to do so, I have put the most rubber possible in a early vega, the pics in my build are actually a 245/45/17 on a 8 inch wide rim, but will need to have the lips trimmed to run them and then would only have a 1/4" of clearance,it rolls around without rubbing but you cant fit the first digit of your finger between the lip and sidewall. I am running a very stiff suspension with large rearswaybar, but I dont endorse my build ideas onto someone who isnt building the same type of goal, so I would say no more then a 235mm tread tire.

The rim width you choose will also effect the tires overall section width, the same 235mm treaded tire on a 7 inch rim will be skinnier then when on a 8 inch rim, the 7 inch will bulge the sidewalls out where as the 8 inch rim will make them more flat.

[NixVegaGT]

Yup that's a certain no on the 8.5" rims with 3.5" backspace like the ones I've got right now. The edge of the rims lines up with the outside edge of the wheel well. I am definitely not pulling that ricer solution of putting tires on a rim that is WAY too wide for the tire and have the edge of the rim hangin' out. That just looks and is dumb to me. To each his own though. It's all cool.

The other thing is you really don't get to use the benefits of the wider rim inside the stock well because you can only fit so much rubber under the lip. I guess it depends on the ride height you want. I'm hoping to get it lower for better racing CG.

[SWT Racing]

A 15x7 wheel will fit darn near perfect. I run a 15x7 Centerline Convo-Pro with a 26x8.5 M/T ET Drag and that is the maximum tire that you will fit in a stock '72 wheelwell without having the tire rub or stick out of the wheel well. You can get away with a bit larger tire if is a radial, because it will not grow significantly at high speeds. My slicks grow enough to rub the front of the wheel opening on the top end of a full pass.