Speedometer Gear Size

[2005 wrangler X ?]

So with my short/very short memory /short buss memory
3.73 gears

I ordered a
33tooth gear and Should have Ordered a 34tooth gear for my 30inch tires being put on on Wednesday
(as ill probably go to 31inch tires when these wear out ill keep the gear)

my question
how far off will my speedometer be off with the 34tooth and 30inch tires
until i can order and get a 34tooth gear

OH and i have the original gear that was in the jeep from the factory (#36 Red) and stock tires were P215/75R15
I changed THAT one out for the 33inch tires he had put on it with the lift but never changed out the gear

thanks
John

 

[2005 wrangler X ?]

according to this ill always be UNDER the speed limit on our sneaky Ocifer radar traps

 

[Rickyd]

The best way to do it is get a gps app for your phone. Do a steady 60 mph and see how many mph off your speedo is. Turn that into a ratio and multiple that by your current gear.

(Speedo reading÷Current speed)×current gear= new gear.

Tires are never the size you think they are. Take them out of the equation and use the important factors. Tooth count and how far off the speedo is

 

[mjonesjr84]

Get the correct tooth gear. Here is the chart from Quadratec.

https://www.quadratec.com/c/reference/jeep-speedometer-gear-tooth-chart