Spedometer Gear?

A

alexgalexg

NAXJA Forum User

Location

Connecticut

• Feb 29, 2020

• #1

98 XJ

automatic
part time t case with sye
3.5 inch lift
General Grabber ATX 265/75 R16



My speedometer is off due to my larger tires I have just installed. I was looking at the charts and am not entirely sure which gear I am supposed to purchase. Can anyone help me? Stock Chrysler 8 1/4 rear end nothing done to that. Tires and wheels are the only thing throwing the speedo off. Thanks

 

A

alexgalexg

NAXJA Forum User

Location

Connecticut

• Feb 29, 2020

• #2

My issue is I cant find an exact equivalent to my metric sized tires and was wondering where I could get a gear that would read spot on with no discrepancy

 

4

4x4JeePmaNthINg

NAXJA Forum User

Location

Colorado

• Feb 29, 2020

• #3

im not sure an exact metric exists. you could get a 30 tooth and maybe read a tad under mph than what your going or step up to the next size and read faster than your really going. as tires wear the size changes and as such I would suggest the latter option.

assuming your using stock 3.55 gears

 

Tim_MN

Freakish Hand Strength

NAXJA Member

Location

Minneapolis, MN

• Feb 29, 2020

• #4

Only Police Package Certified speedometers are spot on. Straight from the Jeep Factory in Toledo, on the Cherokees birthday, the speedometer was already indicating about 3% low.

Google a metric tire size converter, and buy a speedo gear that is close for the tire size and axle gearing.

 

5

5.9longarmXJ

NAXJA Forum User

Location

Jacksonville, FL

• Feb 29, 2020

• #5

T265/75R16
123/120R E
None 3,415 lbs 80 psi 16/32" 54 lbs 7-8" 7.5" 10.5" 8.3" 31.6" 656 US

According to above specs for your tire, it is 31.6" with a tread depth of 16/32, so it potentially wears to 30.6. Base your speedo gear off this, I would recommend basing it on 31" tire size, with 3.55 gears. Problem is there are a bunch of conflicting charts on the internet. Seems 31 or 32 tooth is closest. I would try the 31 tooth.

 

5

5.9longarmXJ

NAXJA Forum User

Location

Jacksonville, FL

• Feb 29, 2020

• #6

As far as spot on perfect. Never gonna happen. You may be a little off, but half an mph to 1 mph off at 70 is not worth complaining about

 

R

RCP Phx

NAXJA Forum User

Location

Phoenix,Az

• Feb 29, 2020

• #7

I would go with the 32t to be a little conservative with your law enforcement officers and it would be easier to justify.

 

techno1154

NAXJA Member

NAXJA Member

Location

In the islands

• Feb 29, 2020

• #8

alexgalexg said:

98 XJ

automatic
part time t case with sye
3.5 inch lift
General Grabber ATX 265/75 R16



My speedometer is off due to my larger tires I have just installed. I was looking at the charts and am not entirely sure which gear I am supposed to purchase. Can anyone help me? Stock Chrysler 8 1/4 rear end nothing done to that. Tires and wheels are the only thing throwing the speedo off. Thanks

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http://gojeep.willyshotrod.com/HowtoSpeedoGears.htm