| Most go kart racers know about gear ratio and | | | | To figure IPR use this equation: Rear Tire |
| racing go kart gear ratio charts are listed in | | | | Circumference(T) x clutch gear(C) divided by rear |
| numerous places. Racing go kart gear ratios are | | | | gear(R) = IPR. For example if one racer(Racer A) |
| figured using the number of teeth on the rear | | | | was running a 15t clutch gear with a 60t rear |
| sprocket of your go kart divided by the number | | | | gear and their tires were 34" the equation would |
| of teeth on the clutch gear on your go kart | | | | be 34 x 15 / 60 = 8.5. This means the kart would |
| engine. For example if you were running a 15t | | | | travel 8.5 inches per revolution of engine. If |
| clutch gear and a 60t rear gear it would be 60 / | | | | another racer(Racer B) had the same gears but |
| 15=4. Simply put this means 1 revolution of the | | | | had 36" tires look what happens. 36 x 15 / 60 = |
| axle to 4 revolutions of the crank. | | | | 9.0. |
| But in order to get a true picture of a racing go | | | | Even though both these racers were using the |
| kart gear ratio a karter must use rear tire | | | | same gears they were not running an equal |
| circumference in the equation. If a kart racer is | | | | set-up. Racer A would be faster coming off the |
| using the same gears as someone else but you | | | | corners and Racer B would be faster down the |
| have 34" rear tire circumference and someone | | | | straight. So what if Racer B wanted to run the |
| else has 36", the true ratios are not equal. To | | | | same IPR as Racer A but still use the same tires? |
| figure the true ratio you will want to use IPR | | | | To figure that we can replace Racer B's 60 with |
| (inches per revolution) which simply means the | | | | Racer A's IPR. 36 x 15 / 8.5 = 63.52. This means |
| number of inches a kart will travel per each | | | | that for things to be equal, Racer B would need |
| revolution of engine. | | | | to change their rear gear to a 63t or 64t. |