31s speedo gear?
Thread Starter
Member
Joined: Jul 2012
Posts: 237
Likes: 1
From: Commerce, MI
Year: 1988
Model: Cherokee
Engine: 4.0
31s speedo gear?
stock tire from the door sticker is 215 75 R15 diameter 27.7"
new tires are General Grabber AT2s 31x10.5 R15 diameter 30.8"
31x10.5/15 = 267/76/15
3.1" difference. The speedo on GPS is between perfect and 3mph slow on expressway. But the calculators say it should be 10.7% slow.
Question is what gear should I replace the stock one with?
My plan is to start tracking 1 tank of gas with the phone GPS and compare the miles to my trip and take that percentage difference. Right now for mpg I am only adding 5% to the miles, because I don't think its 10% off.
new tires are General Grabber AT2s 31x10.5 R15 diameter 30.8"
31x10.5/15 = 267/76/15
3.1" difference. The speedo on GPS is between perfect and 3mph slow on expressway. But the calculators say it should be 10.7% slow.
Question is what gear should I replace the stock one with?
My plan is to start tracking 1 tank of gas with the phone GPS and compare the miles to my trip and take that percentage difference. Right now for mpg I am only adding 5% to the miles, because I don't think its 10% off.
Senior Member
Joined: Mar 2012
Posts: 512
Likes: 1
From: Bellevue, WA
Year: 1998
Model: Cherokee
Engine: 4.0L
Check speed with GPS to verify % difference.
Gear speedo tables are posted everywhere.
Gear speedo tables are posted everywhere.
stock tire from the door sticker is 215 75 R15 diameter 27.7"
new tires are General Grabber AT2s 31x10.5 R15 diameter 30.8"
31x10.5/15 = 267/76/15
3.1" difference. The speedo on GPS is between perfect and 3mph slow on expressway. But the calculators say it should be 10.7% slow.
Question is what gear should I replace the stock one with?
My plan is to start tracking 1 tank of gas with the phone GPS and compare the miles to my trip and take that percentage difference. Right now for mpg I am only adding 5% to the miles, because I don't think its 10% off.
new tires are General Grabber AT2s 31x10.5 R15 diameter 30.8"
31x10.5/15 = 267/76/15
3.1" difference. The speedo on GPS is between perfect and 3mph slow on expressway. But the calculators say it should be 10.7% slow.
Question is what gear should I replace the stock one with?
My plan is to start tracking 1 tank of gas with the phone GPS and compare the miles to my trip and take that percentage difference. Right now for mpg I am only adding 5% to the miles, because I don't think its 10% off.
CF Veteran
Joined: Apr 2008
Posts: 13,952
Likes: 17
Model: Cherokee
Thread
Thread Starter
Forum
Replies
Last Post
ROCKRIDGE 4WD
Vendor Showcase
1
May 23, 2016 06:39 PM
libengan
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
14
Nov 6, 2015 09:16 AM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)