Clueless on wheel backspacing - Need Help

[JWPOORE]

I would like to upgrade my wheels on my 1970 Chevy Blazer 4x4, but I am clueless on what the right backspacing I need for it.

I currently have this:
33x12.50x15 tires, which are what I want to keep on it.
15x10 rims - clueless on it's backspace, 6 lug/5.5

There is a couple of different new rims I have seen for sale that I like, but I'm not sure if the backspacing is correct or will work for my truck:

15x10 with 4.625 inch backspacing
15x8 with 3.625 inch backspacing

Thanks for any help on this matter and suggestions on if either size will work for me or if I need to look for ones with different backspacing. I have tried to research this, but keep coming up more confused.

[LUV2XCLR8]

I'm no expert on this, I know some wheel and tire sites explain it. With that
tire combo and 10" wheels they shouldn't rub anyways. How much lift is it?

[JWPOORE]

Originally Posted by LUV2XCLR8

I'm no expert on this, I know some wheel and tire sites explain it. With that
tire combo and 10" wheels they shouldn't rub anyways. How much lift is it?

I currently don't have any lift on it and the tires/rims fit great. I might eventually put a little lift on it, but for the time being it will stay stock.

[LUV2XCLR8]

Unless you wheel it hard you should have no issues

[pound41]

Take a tape measure and measure the backside of the rim flat spot to edge. Make sure the new rims are the same I learned about this when I was installing rallys that were the same width. The backs were different It looked like one side of the truck was tubbed and one wasn't

[pound41]

Take a tape measure and measure the backside of the rim flat spot to edge. Make sure the new rims are the same I learned about this when I was installing rallys that were the same width. The backs were different It looked like one side of the truck was tubbed and one wasn't

[71RestoRod]

IIRC...

4" backspace is really pushing it to the limit on a 15" rim (but 4" is uncommon in a 15" wheel w/ 6x5.5). Any more than that and you will run up against the tie rod ends. Someone here will start talking about spacers... no sense in going there if you don't have to. 3.625" backspace is most common on these trucks.

[JWPOORE]

Originally Posted by 71RestoRod

IIRC...

4" backspace is really pushing it to the limit on a 15" rim (but 4" is uncommon in a 15" wheel w/ 6x5.5). Any more than that and you will run up against the tie rod ends. Someone here will start talking about spacers... no sense in going there if you don't have to. 3.625" backspace is most common on these trucks.

Thanks for the help. I have a question on the 15x8 rims with 3.625 backspace: Will they work on a 33x12.50x15 tire correctly, or does a 15x10 rim work and look better? I have heard back and forth debates on this with no real conclusion. Some of the tire companys suggest 8.5-10" rims as recommended sizes, but I have seen pictures of people using the 15x8 rim.

These will mainly be driven on the road/highway, so any suggestions would be greatly appreciated.

[Mike C]

I had 15x8 on the Jimmy with 3 3/4 bs. I had 33 14.5 MT Baja Belteds which are a little wider, but they rubbed on the springs at full lock. The 10" rim with 3 3/4" is a better choice.

[71RestoRod]

Originally Posted by JWPOORE

Thanks for the help. I have a question on the 15x8 rims with 3.625 backspace: Will they work on a 33x12.50x15 tire correctly, or does a 15x10 rim work and look better? I have heard back and forth debates on this with no real conclusion. Some of the tire companys suggest 8.5-10" rims as recommended sizes, but I have seen pictures of people using the 15x8 rim.

These will mainly be driven on the road/highway, so any suggestions would be greatly appreciated.

A lot (a whole lot) of guys run 33x12.5 on 8" rims with no issues. The 10" have a deeper dish and IMO look better but the tires start to stick out of the front wheel wells.. which isn't so bad but I think looks goofy on these trucks when the rears don't stick out at all because of the 3+" narrower axle. Again with the spacers but what are you gonna do? It personal preference. Keep in mind that the 10" rims will be much more apt to rub on the "fang" of your front fender.

I went to great lengths to tuck 33" tires completely under the fenders. My rear axle is a D60 and measures the same width as the front axle. The tires are metric 33s on 16x8 rims with 4" backspace. The tread on all four line up right at the edge of the fenders which is exactly what I wanted... but I really would have prefered a deeper dished wheel. I have a set of early period correct Anson slotted mags stashed away that I eventually want to clean up and mount. They measure about 8.5" wide inside the lip and have the 3 5/16" backspace. IMO the best looking wheels ever made but I'm pretty old school when it comes down to it.

[EAST SIDE LOW LIFE]

Here is a diagram .... perhaps it will help.

esll.