Proper backspacing for 20”x12” rear rims

[Pure-Juice]

Hello. I have a 1969 C10 with the narrower rear end and looking to see what backspacing I would need to order a set of 12” wide wheels. The truck will be a fleet side. Currently there is no bed on it so I am unable to take measurements. I will be mini-tubbing the new bed to accommodate the wider rims and tires.

I have done a ton of research on here before posting but I’ve seen answers all over place. From what I can tell, the consensus is 7.5”. I’ve read that is heavy on the conservative side. I wanted to see if anyone is running a 7” or even a 6.75” with success.

Thanks in advance for everyone’s help.

[LockDoc]

Originally Posted by Pure-Juice

Hello. I have a 1969 C10 with the narrower rear end and looking to see what backspacing I would need to order a set of 12” wide wheels. The truck will be a fleet side. Currently there is no bed on it so I am unable to take measurements. I will be mini-tubbing the new bed to accommodate the wider rims and tires.

I have done a ton of research on here before posting but I’ve seen answers all over place. From what I can tell, the consensus is 7.5”. I’ve read that is heavy on the conservative side. I wanted to see if anyone is running a 7” or even a 6.75” with success.

Thanks in advance for everyone’s help.

I don't know if you saw this thread from a week or so ago.

http://67-72chevytrucks.com/vboard/s...d.php?t=798043

LockDoc

[Pure-Juice]

Thanks. I did see that post but I was really hoping to hear from someone who actually has a 12” rear wheel installed rather than relying on educated guesses. Hopefully someone with a similar setup will reply.

[un4gvn!]

Mine are 15x12 with a 7" back spacing. The only modifications I did was to the wheel tubs and I cut the bed floor all the way into the frame rails. I also have wheels that are 15x14 with a 8" back spacing. I didn't put tires on them yet. One thing I didn't like about this set up is the wheel tire combo has a lot of weight. The reason I did this is I race this truck and I needed traction.

[LockDoc]

Originally Posted by un4gvn!

Mine are 15x12 with a 7" back spacing. The only modifications I did was to the wheel tubs and I cut the bed floor all the way into the frame rails. I also have wheels that are 15x14 with a 8" back spacing. I didn't put tires on them yet. One thing I didn't like about this set up is the wheel tire combo has a lot of weight. The reason I did this is I race this truck and I needed traction.

How much room do you have between the inside of the tire and the frame with the 15x12 with a 7" backspace? Also, could you lower the rear of the truck without the outside of the tire hitting the outside of the bed? I'm trying to figure out if I need a 7 or 7.5 BS for mine.

Thanks,
LockDoc

[un4gvn!]

I have just under 3" from hitting the frame and inch and a half from the bed side. I also added on to the splash guard.

[LockDoc]

Originally Posted by un4gvn!

I have just under 3" from hitting the frame and inch and a half from the bed side. I also added on to the splash guard.

Good deal. Thanks for that.

LockDoc

[Pure-Juice]

Un4gven!,

Thank you sir. Exactly the information I was looking for. Congrats on a sweet truck.