Wheel back spacing

[Daleo8803]

Ok guys. I'm wanting to get a set of wheels for my 1966 Chevelle. They will be plain black steel wheels in 16". My question is how do I know I'm getting the right back spacing? I do know that factory steel wheels off of a 1984 S10 blazer ( steel wheels) fit awesome. Any help would be greatly appreciated.

 

[Slacker]

Backspace is dictated by tire width.
Are you putting wide tires on it?

 

[J R Green]

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I'm wanting to put some bigger rollers on a Ranchero and I want them to fill out the wells in height and width.

I'm thinking that a good shop should be able to show you what the end results would be before purchase though.

 

[Daleo8803]

No wide tires. I had a set of 235-70-15 on it. Like how they fill out the wheel wells. I was wanting a tire about a inch shorter in height but on a 16" wheel. If that makes sense.

 

[Johnny]

No wide tires. I had a set of 235-70-15 on it. Like how they fill out the wheel wells. I was wanting a tire about a inch shorter in height but on a 16" wheel. If that makes sense.

You can play with this link and figure it out but at first jab a 235-65-16 is pretty close. You can play with the width (235) and then the percentage of width, the 70 is the sidewall height so 70% of 235mm. Then you can go and figure out if the tire size you really want is even available in the brand you want..

https://www.tacomaworld.com/tirecalc?tires=235-70r15-235-65r16

When you reference S-10 blazer make sure you specify 2wd vs 4wd as I believe thet are different offsets (backspace)

 

[Gear Head]

Backspacing is a wheel measurement and has nothing to do with tire size. Backspacing is measured from the mounting surface of the wheel to the inside edge of the wheel. Higher backspacing will result in a narrower stance as the body of the wheel (not the mounting surface, think hollow barrel) is closer to the centerline of the vehicle. A small backspace number will give a wider stance for the opposite reason.

If you're not wanting to change stance, scrub radius, ect just measure the backspacing on your current wheels and order the same.

 

[rdinatal]

Ideally the center of the rim width should be over the steering pivot. Unfortunately with wide rims you can only go so far inside before the inside rim surface hits the suspension or brakes. Back space is the max you can go to the inside.

Too wide and most of the rim is outside of the steering pivot. Looks stupid too.

 

[Gear Head]

Now if you don't understand how backspacing works you can easily create tire clearance issues which may have been what was being referred to above.

 

[Gazengine]

When you reference S-10 blazer make sure you specify 2wd vs 4wd as I believe thet are different offsets (backspace

The S10 blazers have almost all negative offset-mostly to inside.
If your wheels fit like you want: Lay a bare wheel on the floor face down. Lay a straightedge across the backside and measure down to the mounting surface. This will be your backspacing or negative offset. Then measure through the hub hole down to the floor. This is the positive offset or front spacing.

 

[Jerzsubbie]

Let's get some terminology correct so that were not confusing the OP even more when he's shopping for wheels. Offset and back spacing are not the same thing.

 

[J R Green]

Let's get some terminology correct so that were not confusing the OP even more when he's shopping for wheels. Offset and back spacing are not the same thing.
View attachment 40376 View attachment 40377

Having the pictures reversed in the second row IS confusing.
The top row and the bottom row are set in reverse.

Older vehicles need a negative offset ( less backspace) in order to fill out the wheel wells.

 

[Jerzsubbie]

Having the pictures reversed in the second row IS confusing.
The top row and the bottom row are set in reverse.

Older vehicles need a negative offset ( less backspace) in order to fill out the wheel wells.

Ehhh, just 2 different views, but you have a point.

 

[Jerzsubbie]

Split the pics up to avoid confusion.