Final Gear Ratio, Crawl Ratio, Tire Size Calculators

GEAR RATIO, TIRE SIZE, CRAWL RATIO, ETC. CALCULATORS

This calc can be used to find any (one) missing value.
Solve for your MPH.
Solve for your RPM.
Solve for your Differential Ratio.
Solve for your Tire Diameter.
Solve for your Transmission Ratio.
Solve for your Transfer Case Ratio.
Solve for your Crawl Ratio.

If your tires are bigger than stock you probably, like myself, have spend a lot of time trying to WAG (wild ass guess) your actual MPH when going down the road. If you know your gear ratio and tire size you can get a fairly close idea here. Fill in all entries except the one you want an answer to (in green section).

If you'd like to find your overall crawl ratio, enter the Diff/Trans/TransfCase ratios. Remember, the yellow section (crawl ratio) is only for output only, do not type anything in this box.

Clicking on the Transmission or TransferCase links will jump to bottom of this page.

Formulas used

and

These calculators are color coded by function
All fields Required	Leave ONE field blank	Supply ONLY one field	Results Only

Popular Transmission Ratios

Manual
Transmissions:

AMC SR4 (Borg-Warner) Jeep
	1st	2nd	3rd	4th
	4.07	2.39	1.49	1.00
SM 420
	1st	2nd	3rd	4th
	7.00	3.60	1.70	1.00
SM 465 (MUNCIE) GM, Chevy
	1st	2nd	3rd	4th
	6.55	3.58	1.57	1.00
T-176 Jeep
	1st	2nd	3rd	4th
	3.52	2.27	1.46	1.00
T-177 Jeep
	1st	2nd	3rd	4th
	3.82	2.29	1.46	1.00
T-178 Jeep
	1st	2nd	3rd	4th
	3.00	2.08	1.46	1.00
Mazda 5-spd Ford, Mazda?
1st	2nd	3rd	4th	5th
3.40	2.20	1.50	1.00	0.79
NV3500 Chevy
1st	2nd	3rd	4th	5th
4.02	2.32	1.40	1.00	0.73
NV4500 Chevy
1st	2nd	3rd	4th	5th
5.61	3.04	1.67	1.00	0.73
ZF S6-650 Chevy
1st	2nd	3rd	4th	5th	6th
5.79	3.31	2.10	1.31	1.00	0.76

Automatic
Transmissions:

TH 350 Chevy
	1st	2nd	3rd
	2.52	1.52	1.00
TH 400 GM, Chevy, Jeep
	1st	2nd	3rd
	2.48	1.48	1.00
TH 700R4 GM, Chevy
	1st	2nd	3rd	4th
	3.06	1.62	1.00	0.70
4L80-E Chevy
1st	2nd	3rd	4th
3.10	1.48	1.00	0.75
Allison 1000 Series Chevy
1st	2nd	3rd	4th	5th
3.10	1.81	1.41	1.00	0.71
C-4/C-5/C-6 Ford
	1st	2nd	3rd
	2.46	1.46	1.00
Ford AOD Ford
	1st	2nd	3rd	4th
	2.40	1.47	1.00	0.67
TORQUEFLITE 727 Jeep, Dodge
	1st	2nd	3rd
	2.45	1.45	1.00

Popular Transfer Case Ratios

Dana 300 Jeep
	Lo	Hi
	2.62	1.00
Borg Warner 1356 Ford
	Lo	Hi
	2.69	1.00
DANA/Spicer 18 Jeep
	Lo	Hi
	2.46	1.00
DANA/Spicer 20 Jeep, IH (TC-145), GM, Ford
	Lo	Hi
	2.00	1.00
NP 203 Chevy, Ford, Dodge
	Lo	Hi
	2.00	1.00
NP 205 Chevy, Ford, Dodge, IH
	Lo	Hi
	1.98	1.00
NP 207/208 Jeep, Chevy, Ford, Dodge
	Lo	Hi
	2.61	1.00
NP 231 Jeep (YJ)
	Lo	Hi
	2.72	1.00
Toyota (67-74) Land Cruiser
	Lo	Hi
	2.31	1.00