Gear Ratio & Tire Size Chart

Considering making modifications to your Jeep? Whether it is changing an axle or going with different tires this chart is helpful in finding the right Tire Size to Gear Ratio that you need to achieve the optimal performance for your particular application.

Also, when making altering your factory gear ratio or wheel size your speedometer and odometer may read incorrect. Make the necessary changes to your speedo by replacing your Jeep Speedometer Gear .

A basic method to calculate is to mutiply .12 by your tire diameter. (.12 X 38" = 4.56)

The below table can be used to get a rough idea on gear ratios. The colors represent ideal RPM's at highway speeds (65). These calculations are assuming a manual transmission with a 1:1 ratio. If you drive an automatic your RPMs will be slightly higher, and the opposite is true if you have overdrive (your RPMs will be slightly lower).

Highway cruising and best fuel economy stay towards the yellow (2600 rpm)
Around town daily driving is color coded green (2800 rpm)
Better towing power or just more 4-low power use the ratios near the red (3100 rpm).

Find your Gear Ratio
Tire Size
 
3.31
3.42
3.55
3.73
3.91
4.11
4.27
4.56
4.88
5.13
5.29
5.38
5.71
6.17
7.17
27"
267727662872301731633325345436893947415042794352461949915800
28"
258226682769290930503206333135573806400141264196445448135593
29"
249325762674280929453095321634343675386339844052430046475400
30"
241024902584271528462992310933203553373538513917415744925220
31"
233224092501262827552896300832133838361437273790402343475051
32"
225923342423254626962805291431123331350136103672389742114894
33"
219122632349246925882720282630183230339535013561377940934745
34"
212621972280239625122640274329293135329533983456366839634606
35"
206521342215232824402565266428453045320133013357356338504474
36"
200820752154226323722493259027662961311232093264346437434350
37"
195420192095220323082426252026922881302831233176337036424243
38"
190219662040214422472362245426212805294830403092328235464121
39"
185419151988208921902302239125542733287329623013319834554015
40"
180718671938203721352244233124902664280128882937311833693915
41"
176318221891198720832189227524292599273328182866304232873819
42"
172117781846194020332137222023712538266827512798296932083728
43"
168117371803189419862087216923162479260626872733290031343642
44"
164316981762185119412040211922632422254626262670283430633559
bubble-icon
Let's Chat