10.5 Slick 68-69 Skylark

Thanks Mike..

 

So it seems like 5.5- 5.75 bs is about all we can get away with.....if one would find from with 6 or 6.5 bs could a shim spacer be used to get the wheel back to correct position and still be safe.

Just the flat shim plate that would sit behind the flange.......not an adapter to change pattern

 

I don’t like to run any type of shims or spacers on the rear wheels,as it can add more stress to the wheels studs.
I would just stick with 5.5” backspace. You also need to reduce or eliminate any excessive body roll,which is very common with these cars. Good control arms,sway bar or anti-roll bar,bushings,etc. all make a difference and will keep the tires from rubbing the insides.

 

Spoke to my friend w holeshot wheels.
He uses 15x9
5.5 back space
72 Cutlass Mickey Thompson radial 295/65/15.
Another option here 9” wheels.
They work great. Car flies.

 

Also watch how shock bolts on.
Always check your clearances before letting car down off stands. If you use wheel screws could pose an issue w 5.5” wheels.
I never use them.

 

Hoosier says that 29x10.5-15w tire fits and 8-10 rim......8m certain going from 8-10 rim that the tread will be flatters but the section width will be wider too.....
Wonder if the best bet is to try them on what have then if the fit look to try wider rims.

 

summit brand sells nice 15x10 with 5.5” backspace for a good price.

https://www.summitracing.com/search...eywordMatch&SortOrder=Ascending&keyword=15x10

I would use a 10” rim for sure it will really widen the contact patch and make for more even tire wear. Here is a photo of the same 295/50R15 (10” wide) tires on both 15x8 and 15x12 wheels, much wider contact patch as you can see. I use them for the chassis Dyno.

 

Not sure the reasoning for 29/10.5W tires.
I use 295/65/15 Hoosier radials on 10” hole shots. 10” tread. They are about 10 pounds lighter per tire. I go 1.31-1.35 on them off foot brake 3800+ pounds.
Whatever you choose best to you.

 

I had looked at those, very similar to the prostar look......just wonder if they would hold up under the use of dragracing.......there has to be a reason they are less than half the price....that worries me a little

 

My main reason for looking at the tore wasn't so much the extra width but the fact they are a stiff sidewall.

That dr2 tires has very similar specs in the catalog as my current 29x10....the dry is slightly taller. Great news they work that well. Can I ask what suspension setup you using under there and engine size, just to be curious.

I know my setup is slower in the 60ft than it can/should be by close to a tenth maybe more. Just haven't really had the time to make weeks of back to back track trips to get it ironed out......I know my sidewalls are taking a beating.....I can see it in the videos and pictures.......this has been an issue for awhile.

 

I had these ones below on my old 70 Skylark that I sold.

https://www.summitracing.com/parts/sum-561p-51610

I sold the car with a 600 HP turbo Buick 350 and the guy swapped in a 383 with turbos that’s 1000 HP. It’s been reliable for 6 years now running 9s in the quarter at 4000 pounds, same wheels still.

 

Well that's good to know, and a full set can had be had for 550ish.

 

Oh and I do remember weighing them and they are heavier than the ones they are simulating, this could cost a bit of ET or not its tough to say in the real world.

 

I didn't notice any gains when I swapped from steel......but since you said it. Lol

 

I have the complete H&R Parts rear suspension.
Anti roll, double adj uppers and + 1/4” lowers which help center wheel. Moog 5379s. Moser 9”
555 Big Block Chev in a 70. Chevelle holeshot wheels 10” 5 7/8 backspace. Rear is little extra wide n 1/8” spacers w 5/8 studs.
Front suspension Gm springs and afco 80/20s w del a lum bushings.
Not scienced out. Back yard built. Car works.

 

Guys, i went with the recommendations of 5.5 inch backspace on 15x10 inch wheels, mounted Mickey Thompson drag radial pros - 275/60/15.....,they dont fit. Need more back spacing. My rear end is exactly centered in my 72 GS. Even 6 inch back spacing would barely accommodate this tire combo without cutting wheel well lips.
With these wheels/tire combo mounted, i had 1 inch of space between frame and tire sidewall on the inside, 3/8-1/2 inch interference with the outer wheel well lips.
What i learned is you cant believe everything you read on the internet.
Im trying to sell this tire and rim combo, go with the 15x8 wheels with 5.5 inch back spacing and a smaller drag radial.
Fyi - these MT drag radial pros are 12.5 inches wide at tire cross section when mounted on a 10 inch rim.

Live and learn

 

With Alfs rear setup my tire actually tucks up inside the wheel well more than most do......so my lip sit just about at the fat part of the sidewall

 

Larry, using an 8 inch rim which is 9 inches wide overall, remember back spacing is measured from outside of rim, an 8 inch rim with 5.5 inches back spacing will on my vehicle have 1.75 inches rim to frame on inside, 2.25 inches wheel well to outside rim clearance. So for an over the shelf rim from summit, i think this will be a good fit. Looking at it now, an 8 inch rim with 5 inches back spacing will have 2.25 inches clearance on the inside, 1.75
On the outside. Given body seay etc, maybe its better to have the 5.5 inches back spacing on the 8 inch rim ....maybe its 6 to one, half dozen to the other.
These MT drag radial pros must be wider than a standard rated tire.....275/60/15....12.5 inches wide at cross section of tire. No way they will fit.

 

My 8" rims with standard length 8.5 axle has 4.5" backspacing. When I ran regular control arms I would sometimes rub but inside and outside........on 29x10s. After the alf rear setup there is no more rubbing. Much less deflection even in corners