33x12.50x20 with 4.56 gears 6 speed?

Bfox111

Member
Jan 12, 2011
42
0
6
Georgia
Is anyone running 33s with 4.56 gearing and the 6 speed alli? How does it do on the interstate? RPM @ 70? 80? Im wanting to go smaller with my tires. Im currently on 37s. I dont want to regear unless i have to. Or does anyone know a good site i can use as a calculator that will take into consideration the internal gearing of the allison? Thanks
 

Ridin'GMC

I like red
May 20, 2010
614
5
18
MA
33" I'd use stock 3.73 gears. 35" I'd use 4.10s. 37" 4.56 is perfect. All in those I said is because the driveability would be better in towing and daily driving. I had 33 on 3.73 and it was perfect. 35 on the 3.73 was a bit lugging for towing. Now I have 37's and they suck on 3.73. I'm still running 3.73, soon will be upgrading to 4.56 to help with towing. Those are better for 6 speed transmission.
 

GMC 08

Member
Aug 2, 2010
40
0
6
St. Charles, MN
I just regeared 3.73 to 4.30 I made my own calculator and it was very close.

33" Tires with 4.56 gears @80 you would be at 2366 RPMS
33" Tires with 4.10 gears @80 you would be at 2127 RPMS
33" Tires with 3.73 gears @80 you would be at 1935 RPMS

Stock with 265-70r17 (31.6") @80 would be around 2005 RPMS