Speedometer gear question

[Whitaker717]

I am running about 5 mph slow on my speedometer. My cable needs replaced I think because it ticks up to about 25 then flattens out. I am running 235 75 15 tires. Would that make me run slow like that? I believe I have the Dana 355. Do I need to change out the gear?

[eaglescout526]

Like the speedo gear itself in the trans? That gear is supposed to be changed out when you go up in tire size. 

[Whitaker717]

Yea that’s what I was wondering. The bigger tires were in there when I bought it. What size gear should I get. I’m going to change the speedometer cable out too while I’m at it unless changing the gear will stop the ticking or jumping. 

[eaglescout526]

There was something in the FSM regarding this actually. I would have to find it unless someone beats me to it.

[fiatslug87]

[Whitaker717]

Somewhat of another silly question but do they make gear sizes according to this chart? Like 34 teeth, 33 teeth or do you just get a size close to what you need. Thanks for the chart that’s awesome