Gear Ratio / Tire Size Table
Good "rule of thumb" calculation is to mutiply .12 by your tire diameter. (.12 X 38" = 4.56)
(see more formulas at bottom of page)
The below table can be used to get a rough idea on gear ratios. The colors represent ideal RPM's at highway speeds (65). For highway cruising
and best fuel economy stay towards the yellow (2600 rpm), around town daily driving is color coded green (2800 rpm),
and for better towing power or just more 4-low power use the ratios near the red (3100 rpm). These calculations are assuming a manual transmission with a 1:1 ratio. If you drive an automatic your RPMs will
be higher, and the opposite is true if you have overdrive (your RPMs will be lower).
|
Gear Ratio |
T i r e
D i a m e t e r
|
|
|
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" |
|
2677 |
2766 |
2872 |
3017 |
3163 |
3325 |
3454 |
3689 |
3947 |
4150 |
4279 |
4352 |
4619 |
4991 |
5800 |
28" |
|
2582 |
2668 |
2769 |
2909 |
3050 |
3206 |
3331 |
3557 |
3806 |
4001 |
4126 |
4196 |
4454 |
4813 |
5593 |
29" |
|
2493 |
2576 |
2674 |
2809 |
2945 |
3095 |
3216 |
3434 |
3675 |
3863 |
3984 |
4052 |
4300 |
4647 |
5400 |
30" |
|
2410 |
2490 |
2584 |
2715 |
2846 |
2992 |
3109 |
3320 |
3553 |
3735 |
3851 |
3917 |
4157 |
4492 |
5220 |
31" |
|
2332 |
2409 |
2501 |
2628 |
2755 |
2896 |
3008 |
3213 |
3838 |
3614 |
3727 |
3790 |
4023 |
4347 |
5051 |
32" |
|
2259 |
2334 |
2423 |
2546 |
2696 |
2805 |
2914 |
3112 |
3331 |
3501 |
3610 |
3672 |
3897 |
4211 |
4894 |
33" |
|
2191 |
2263 |
2349 |
2469 |
2588 |
2720 |
2826 |
3018 |
3230 |
3395 |
3501 |
3561 |
3779 |
4093 |
4745 |
34" |
|
2126 |
2197 |
2280 |
2396 |
2512 |
2640 |
2743 |
2929 |
3135 |
3295 |
3398 |
3456 |
3668 |
3963 |
4606 |
35" |
|
2065 |
2134 |
2215 |
2328 |
2440 |
2565 |
2664 |
2845 |
3045 |
3201 |
3301 |
3357 |
3563 |
3850 |
4474 |
36" |
|
2008 |
2075 |
2154 |
2263 |
2372 |
2493 |
2590 |
2766 |
2961 |
3112 |
3209 |
3264 |
3464 |
3743 |
4350 |
37" |
|
1954 |
2019 |
2095 |
2203 |
2308 |
2426 |
2520 |
2692 |
2881 |
3028 |
3123 |
3176 |
3370 |
3642 |
4243 |
38" |
|
1902 |
1966 |
2040 |
2144 |
2247 |
2362 |
2454 |
2621 |
2805 |
2948 |
3040 |
3092 |
3282 |
3546 |
4121 |
39" |
|
1854 |
1915 |
1988 |
2089 |
2190 |
2302 |
2391 |
2554 |
2733 |
2873 |
2962 |
3013 |
3198 |
3455 |
4015 |
40" |
|
1807 |
1867 |
1938 |
2037 |
2135 |
2244 |
2331 |
2490 |
2664 |
2801 |
2888 |
2937 |
3118 |
3369 |
3915 |
41" |
|
1763 |
1822 |
1891 |
1987 |
2083 |
2189 |
2275 |
2429 |
2599 |
2733 |
2818 |
2866 |
3042 |
3287 |
3819 |
42" |
|
1721 |
1778 |
1846 |
1940 |
2033 |
2137 |
2220 |
2371 |
2538 |
2668 |
2751 |
2798 |
2969 |
3208 |
3728 |
43" |
|
1681 |
1737 |
1803 |
1894 |
1986 |
2087 |
2169 |
2316 |
2479 |
2606 |
2687 |
2733 |
2900 |
3134 |
3642 |
44" |
|
1643 |
1698 |
1762 |
1851 |
1941 |
2040 |
2119 |
2263 |
2422 |
2546 |
2626 |
2670 |
2834 |
3063 |
3559 |
|
Here are some common gear formulas:
This page was created by Mark Medina.