DCSpecial
Mr. Sinister
- Joined
- Apr 23, 2006
- Messages
- 3,898
The question gets brought up often with lifted trucks regarding gearing choices with bigger than stock tires.
I've complied a little chart of sorts that shows how different gear ratios efffect RPMs with different sized tires.
Here's some info I posted awhile back in another post on another forum:
Here's a quick example of rpms with given gear ratios at 70 mph. All rpms listed are for a AOD trans with a .70 OD ratio....so they aren't dead on, but they are close (the 4R100 has a .71 or .72 OD ratio I think??). So, while the rpms aren't 100% on the money it will give you an idea of how each different gear ratio effects engine rpm at 70mph.
tire..............gear...................rpm
31.6"...........3.73....................1943 (stock truck)
31.6............4.10....................2136
31.6............4.30....................2240
34.7............3.73....................1770
34.7............4.10....................1945
34.7............4.30....................2040
34.7............4.56....................2164
36.7............3.73....................1673
36.7............4.10....................1839
36.7............4.30....................1929
36.7............4.56....................2046
36.7............4.88....................2189
38...............3.73....................1616
38...............4.30....................1863
38...............4.56....................1976
38...............4.88....................2114
38...............5.13....................2223
40...............4.10....................1688
40...............4.30....................1770
40...............4.56....................1877
40...............4.88....................2009
40...............5.13....................2112
42...............4.56....................1788
42...............4.88....................1913
42...............5.13....................2011
42...............5.38....................2109
44...............4.56....................1706
44...............4.88....................1826
44...............5.13....................1920
44...............5.38....................2013
46...............4.56....................1632
46...............4.88....................1747
46...............5.13....................1836
46...............5.38....................1926
I have most common choices pretty well covered....if you want info on a gear/tire combo that I don't have listed let me know and I'll add it to the list.
I've complied a little chart of sorts that shows how different gear ratios efffect RPMs with different sized tires.
Here's some info I posted awhile back in another post on another forum:
Here's a quick example of rpms with given gear ratios at 70 mph. All rpms listed are for a AOD trans with a .70 OD ratio....so they aren't dead on, but they are close (the 4R100 has a .71 or .72 OD ratio I think??). So, while the rpms aren't 100% on the money it will give you an idea of how each different gear ratio effects engine rpm at 70mph.
tire..............gear...................rpm
31.6"...........3.73....................1943 (stock truck)
31.6............4.10....................2136
31.6............4.30....................2240
34.7............3.73....................1770
34.7............4.10....................1945
34.7............4.30....................2040
34.7............4.56....................2164
36.7............3.73....................1673
36.7............4.10....................1839
36.7............4.30....................1929
36.7............4.56....................2046
36.7............4.88....................2189
38...............3.73....................1616
38...............4.30....................1863
38...............4.56....................1976
38...............4.88....................2114
38...............5.13....................2223
40...............4.10....................1688
40...............4.30....................1770
40...............4.56....................1877
40...............4.88....................2009
40...............5.13....................2112
42...............4.56....................1788
42...............4.88....................1913
42...............5.13....................2011
42...............5.38....................2109
44...............4.56....................1706
44...............4.88....................1826
44...............5.13....................1920
44...............5.38....................2013
46...............4.56....................1632
46...............4.88....................1747
46...............5.13....................1836
46...............5.38....................1926
I have most common choices pretty well covered....if you want info on a gear/tire combo that I don't have listed let me know and I'll add it to the list.
Last edited: