64 – 65 Front wheel back spacing?

I’m going to lay down my hard earned cash for new wheels & tires and was looking for more info on front wheel back spacing. I’ve saved nearly every post concerning 64 – 65 tire fitment for the last 2-1/2 years, most of which deal with rear tire size and wheel back spacing.

Here's my combo:
65 Chevelle with stock width rear end, drum brakes all around (I plan on switching to front discs next winter), Eibach lowered springs 1-1/2” front & 1” rear, and polygraphite bushing all points front & rear.

I going to buy 16” American TT II’s, 16 x 7 fronts with either 235 or 225 50 16’s.
What backspace do I need for these to clear everything? I’ve seen that 65elcamino (Brian) recommends 4-1/2” backspace for 7” wide fronts, but American can only make 4-1/4” backspace in the 16 x 7’s. Will this work OK? Which tire would fit better? Would switching to disc spindles move the wheel farther outboard?
I wish I had measured the front wheelwell clearances before I took off the sheet metal for painting, but hindsight is always 20-20.

Just for reference I plan on 16 x 8’s with 4-3/4” backspacing for the rears with 245 50 16’s.

Thanks in advance for your responses, this site is the best damn source of info anywhere!


Jeff

I have a 64 chevelle convertible. I converted to front discs brakes a number of years ago. I want to go the resto route with factory steel wheels, red lines and dog dish hub caps. Because of my updated drivetrain, i.e. 350cid, m-22, and 12 bolt rear, i want to put the largest tire in the fender wells. I contacted Coker Tire, told them my wishes and they were very helpful in determaning my wants. However, I'm not sure if they deal with the sizes you mentioned. You can reach them at 1-800-251-6336. It's worth a try. Good luck.

Jeff,

The 4.25 bs wheels should work fine on the front with the 235mm tires, but you might have minor rubbing durng turns snce you are lowering it 1-1/2". The 225mm tires should not rub, but not sure due to the lower stance. The disk brakes move the wheel out 1/4". The rears should be good with the 245mm tires, 255mm might fit okay as well. You should end up with 3/4" clearance on the outside and 1" on the inside if you use a 255mm rear tire with your 4-3/4" bs, more with the 245mm tire.

On the front, I have 8" wide with 5" bs wheels, 245mm tires, 72 disk brakes, and 1' lowering springs. I have minor rubbing during turns when hitting bumps, but no damage is done to the wheelhouse or tire.

On the rear, I have 17X8 with 5"bs, 255mm tires, 1/2" lower via cut 1/2 coil. The wheel is centered in the wheelhouse ad I have 1" clearnace on the outside and 3/4" on the inside.

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Brian TC#1092, ACES#4374
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1965 El Camino (http://www.chevelles.com/showroom/65elcamino1b.jpg) Before Restoration (http://www.chevelles.com/showroom/65elcamino1a.jpg)
1981 Corvette (http://www.chevelles.com/showroom/65elcamino81.jpg)

Brian thanks for the reply, how close does the overall section width of your tires compare to the section size printed on the tire? I've read that some brands of tires run
sightly wider than while other brands run small. Thats why I decided to go with the 245 width for the rears plus the fact that my wheel wells measure 11-1/2" at their widest point. I spent a lot of time measuring the rears and was worried that if I got a set that ran wider than 255 I could have problems.

I'm glad to hear that the fronts should work OK.

Jeff

Jeff65SS:

I'm not sure if there is a diameter you are trying to achieve. Consider 245/45/16 on a 16x8 inch rim with 4.75 to 5.0 of BS. Should work fine on a car lowered as minimally as yours, assuming that was 1.5" from stock, not 1.5" lower than old and saggy.

For me, the rubbing point would have been my 1 3/8" sway bar at full turn lock. But with the 245/45/16 (or probably 245/50/16) it wouldn't have.

If I were you, I'd buy the rears first and try them on the front for final fitment. (That's how I found my sway bar rubbing when I tried the 255/50/16 on the fronts). Then, you'll see that you had more room than you think. Many people run 245/50/16 on all four corners of a '65.

As for the rears, my 255/50/16's measure 10.4" when mounted on 16x8 (Dunlop SP-8000) per manufacuturers spec. With your 11.5" of room, that's easy and gives an enormous 0.5" of clearance per side.
Hope this helps.

jlaf

Thanks jlaf, I did a search on posts by you and found a lot of good info on tire sizes. Looks like I need to do a little more research on the Tire Rack site. The Dunlop's your running look like a pretty good tire for the price.

Jeff

You're quite welcome JEFF65SS. I'll stay tuned in for more questions this critical tire purchase. I should have pointed you to a search on my discussions since I've covered some of these points in detail in the recent past in this forum. Glad you found it.

As some additional info: my 245/45/16 Dunlop SP8000 measure 9.8" section width on a 16"x8" wheel. Manufacuteres spec says it should measure 9.6". So, as you mentioned some tires measure more than spec even when accounting for the 0.2" growth per 0.5" rim width. I've found that the section width grows more than this age-old-rule for lower profile tires.

As for the Dunlop SP8000's they serve autocross duty and are cheap enough to abuse. On my real autocrosser (non-chevelle) I use Bridgestone Potenza S-03 Pole Position tires (the finest street tire made in my opinion if you're spending some bucks). Hopefully you're not dead-set on BFG ZR's as they are an overpriced/outdated/underpreforming design. (But hey, in 1987 on a brand new IROC they were probably the real deal.)

And, this is the least I could do for the guy (*you*) that gave me '66-'67 BBC shroud measurements a few weeks ago in "Heating and Cooling". Thanks again.

jlaf