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Mopar Speedo Gear Chart : Drivin' It Home (drivinithome.com)
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Mopar Speedometer Pinion Numbers
Tire Overall Diameter
|
AXLE RATIO |
24" | 26" | 28" | 30" |
| 2.76 | 2538930 | 2538928 | 2538926 | 2538924 |
| 2.94 | 2538932 | 2538930 | 2538928 | 2538926 |
| 3.21 | 2538935 | 2538933 | 2838931 | 2838929 |
| 3.55 | 2538939 | 2538936 | 2538933 | 2538931 |
| 3.91 | 2538943 | 2538940 | 2538937 | 2538935 |
| 4.10 | 2538945 | 2538942 | 2538939 | 2538936 |
| 4.30 | 2538944 | 2538941 | 2538938 | |
| 4.56 | 2538945 | 2538943 | 2538940 |
Please note: these numbers are for the standard style pinion gear
also last two numbers are the number of teeth, 2538945 = 45 teeth
How to Calculate tire diameter: Example 265/60/15
265mm/25.4mm = 10.43 Inches Section Width
10.43 in. X 60% = 6.25 in. Side Wall thickness
6.25 in X 2 = 12.5 in Total Side wall height
12.5 " + 15" (rim Size) = 27.5" Diameter
So with this Tire size and 3.55 Gears, I would use 35 Tooth Speedometer gear.
