Smaller Tires
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5 Year Member
Joined: Jun 2018
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Smaller Tires
I got a good deal on Michelin's but they are 245-70-17........I had 265-70-17's
Could someone who is good at math tell how that would affect odometer, I was thinking a couple of miles per 100 did not know if it was worth having odometer re calibrated by garage.
I called dealer they won't and I don't have forscan but was told local garages can.
Could someone who is good at math tell how that would affect odometer, I was thinking a couple of miles per 100 did not know if it was worth having odometer re calibrated by garage.
I called dealer they won't and I don't have forscan but was told local garages can.
5 Year Member
Joined: Dec 2015
Posts: 1,825
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From: Brantford Ontario
you also can do it with a better tuner/scan tool.....by changing the height of your tires.....others that know which ones probably will chime in to help??
Also go on one of the tire suppliers that have a tire calculator & find out just what the actual difference is....it may not be worth all you are worrying about....Should be in the area of 1-3 mph...
Also you will have slightly better get up & go but it's probably not too noticeable ??
Also go on one of the tire suppliers that have a tire calculator & find out just what the actual difference is....it may not be worth all you are worrying about....Should be in the area of 1-3 mph...
Also you will have slightly better get up & go but it's probably not too noticeable ??
Senior Member
Joined: Jun 2020
Posts: 121
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From: Ohio
When your speedo is at 65 you'll actually be going 62.73.
https://tiresize.com/speedometer-calibration/
You'll also have an extra 23 revolutions per mile with the change in size, I'm not sure how much they affects the odometer.
https://tiresize.com/speedometer-calibration/
You'll also have an extra 23 revolutions per mile with the change in size, I'm not sure how much they affects the odometer.
Last edited by mantelope; Apr 29, 2022 at 05:51 PM.
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The tires are about 3.5% smaller. Your speed and odometer will read fast by 3.5%.
Odometer is less critical given the large sample size. Your speed will be an instant error.
If you are set on 5000 mile oil changes, you'll have to wait for your odometer to go 5200 miles.
These are rough numbers based only on math. The actual tire could be larger or smaller than the math would indicate.
Odometer is less critical given the large sample size. Your speed will be an instant error.
If you are set on 5000 mile oil changes, you'll have to wait for your odometer to go 5200 miles.
These are rough numbers based only on math. The actual tire could be larger or smaller than the math would indicate.
Thread Starter
5 Year Member
Joined: Jun 2018
Posts: 46
Likes: 4
When your speedo is at 65 you'll actually be going 62.73.
https://tiresize.com/speedometer-calibration/
You'll also have an extra 23 revolutions per mile with the change in size, I'm not sure how much they affects the odometer.
https://tiresize.com/speedometer-calibration/
You'll also have an extra 23 revolutions per mile with the change in size, I'm not sure how much they affects the odometer.
The tires are about 3.5% smaller. Your speed and odometer will read fast by 3.5%.
Odometer is less critical given the large sample size. Your speed will be an instant error.
If you are set on 5000 mile oil changes, you'll have to wait for your odometer to go 5200 miles.
These are rough numbers based only on math. The actual tire could be larger or smaller than the math would indicate.
Odometer is less critical given the large sample size. Your speed will be an instant error.
If you are set on 5000 mile oil changes, you'll have to wait for your odometer to go 5200 miles.
These are rough numbers based only on math. The actual tire could be larger or smaller than the math would indicate.
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Adjusting for a 3% variance is difficult.
The math on this tire is 30.5" vs 31.6". Depending how thick the tread is, that's 25 to 40% of the difference in tire. A new tire of your new size vs. a bald set of your old size is close in size.
You would need FORScan to adjust the code to get it as close as possible which takes a few different inputs to dial it in. Any plug and play setup will be a mathematical guess (it will say your new tire is 31.6" tall if you enter the numbers...... however your actual tire may only be 31.4". Therefore, still inaccurate but maybe as much as 2% instead of 3.5%.
Get setup with FORScan and play with it or leave it as it -I wouldn't use any "input your tire size here" devices as a 'fix' for your exact inaccuracies.
The math on this tire is 30.5" vs 31.6". Depending how thick the tread is, that's 25 to 40% of the difference in tire. A new tire of your new size vs. a bald set of your old size is close in size.
You would need FORScan to adjust the code to get it as close as possible which takes a few different inputs to dial it in. Any plug and play setup will be a mathematical guess (it will say your new tire is 31.6" tall if you enter the numbers...... however your actual tire may only be 31.4". Therefore, still inaccurate but maybe as much as 2% instead of 3.5%.
Get setup with FORScan and play with it or leave it as it -I wouldn't use any "input your tire size here" devices as a 'fix' for your exact inaccuracies.
10 Year member
Joined: Jan 2015
Posts: 120
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From: Edmonton Alberta
I use winter tires in the 245 size you mentioned, they were from my previous truck and only one year old when I traded in for my 2015. Other than the minor difference to the speedo, there are no problems with the 245 size. It is also the standard size tire or was on the base XL trucks