gear ratio/tire math, what ring gear do i have?

[yukon25008.1]

Very curious to know how the math goes to figuring out how much your gear ratio is affected by tire size?

If i have 4;10,s andd run a 33" tire.. am i ddown to 3;73.. or a 35" tire..does it go ddown to a 3;55?

Finally with 4;56,s in and a 35" tire how will my rpm,s be?

 

Also how do i determine what ring gear i have, 10.5 or 11.5. Its an odd shaped 14 bolt, w/4;10,s and an 8.1/allison combo up front..

[hockeypro1411]

http://www.4wheelpar...gear_ratio.html

 

Should clear some of those questions up for ya!

 

As for the ring gear, I do believe the D-Max/Allison and the 8.1/Allison combos came with the 11.5" ring gear. All other HD's have the 10.5".

[yukon25008.1]

Thanks, man..That was pretty helpful

[00Silverado4x4]

http://www.4lo.com/

 

This is a site, I've used for various calculators.

[Diesail]

Look at the RPO codes in your glove box. Here is a list that a quick google search came up with. http://www.drivetrain.com/parts_catalog/ring_and_pinions/what_gear_ratio_do_i_have_in_my_gm_or_chevrolet.html

[ATMINF]

_{I thought that the big blocks also had the 11.5 rear? I know that if you look at the numbers that is why the big block Suburbans got the 4L85E vs 4L80E. In the pickups I know that you could also get a Ally trans behind a Big Block and he tow ratings were the same for both the D-Max and Big Block.}