Speedo Gear

[ItchyDong]

I'm putting BFG T/A KM3 33X10.50X15's on the Jeep after a regear to 4.56. The specs on the tire measure a true diameter of 32.5" brand new. Should I go with a 39 tooth, or 40 tooth?

 

[Jerry Bransford]

39.

 

[CharlesHS]

I would go with the 40 since as the tire’s wear down and the tires diameter gets closer to 32” the correctness of the actual speed will become closer not further if you used the 39.

 

[ItchyDong]

Thanks Jerry!

 

[ItchyDong]

I would go with the 40 since as the tire’s wear down and the tires diameter gets closer to 32” the correctness of the actual speed will become closer not further if you used the 39.

I see what you're saying. That was my original line of thinking too. But what I'm concerned with is - will the 40 tooth make me speed until the tires wear down enough for it to be closer. The specs are 18/32" tread depth, so we're talking almost half the tread is gone before it finally meshes up with the gear specs.

Idk, I'm pre-coffee right now. My ears are smoking. I'm going with Jerry

 

[CharlesHS]

I understand Jerry’s and your reasoning.
You just need to figure out and remember how much slower the speedo is indicating in relation to actual so you do get speeding tickets.