Ring size for diff on '85 suburban?
 

I put new 37 inch tires on my 1985 6.2 suburban and now I want to re-gear the front and rear diffs. I was thinking a 4.56 ratio would be good but I don't know what size rings are in each. Any advice is much appreciated. Thanks!

Is it a 1/2 or 3/4 ton? If you want to know the ring gear size you'll have to identify what front and rear ends you have. Most likely 10 bolts in a half ton (8.25" ring gear) 3/4 would have a 14 bolt rear (10.5") and a 10 bolt or possibly a D44 front.

It's a 3/4

4:56 is a good choice for a stock 6.2. 4:10 would be ok if you're just highway driving. If your hitting the trails I'd go 4:56.

Oh and a 10 bolt is a 8.5" not 8.25. I was thinking ifs.

I have 4.10 in there now and with the 37s it's painfully slow in any situation and works everything much harder than it should. I figured 4.56 would be a good all around choice

You will be happy with the 4.56's running 37'' tires. I did the same thing on my truck.