Speedometer & ODO off?

Hi TW,

I have a quick question. I upsized my tire from 265/65R17 to 265/70R17..

Since I up-sized my tire I understand that I will actually be going a mile or 2 faster than the listed speedometer.

Would the larger tire affect my ODO to? If I put 100,000 miles on my tacoma with the upsize tires. If it reads 100k would it mean I actually drove slightly more or slightly less?

Thanks in advance!

 

The 265/70/17 are about 99 inches in circumference. The 265/65/17 are about 96 inches. When Your speedometer and odometer thinks you have travelled 96 inches you have actually traveled 99 inches. So if you’re on 265/70/17 tires, and your odometer reads 96,000 mile, your truck has traveled 99,000 miles. The same goes for velocity. If your speedometer reads 96 you are traveling at 99 mph. Reading 32 mph translates to 33 mph. These are approximations.

 

Thanks for the answer.. my OCD self is trying to decide if I should have it re calibrated or ignore it!

 

Compare it to speed over ground with a phone app if possible.

Factory tolerance for speedo accuracy is +/- 5% from a rolling dyno operator I met. I had to deal with a speeding ticket last year so I took the truck to get the speedometer checked for accuracy specifically with a 265/70/17 tire upgrade.

Here's a link to my results from the dyno.

https://www.tacomaworld.com/threads/speedometer-off.435381/#post-12591638

 

My speedometer, with 285/75/16, is 1 mph off at 65mph

 

Check out your speedo/odo against a GPS.

It's not impossible that the new tires corrected the factory error. Or made it worse.

 

I've heard many times on this forum that 265-65-17 to 265-70-17 actually makes the speedometer more accurate.. Can anyone attest?

 

See post 6.

What worked for others may not work for you. Depends on what yours was to begin with.

 

I have a first gen, but for me, going from 31's to 32's did make my speedo more accurate. It's 1-2 mph off with 31's, but almost dead on with 32's.

 

Depends on how accurate you are from the factory with stock tires, like I said in post 4, factory tolerance is roughly +/- 5%.

To eliminate confusion in my link, stock OR tire is 265/70/16 so a +1 is a 265/75/16, same diameter as your 265/70/17.

 

there is always this tool. ordered one for myself today.

http://www.hypertech.com/vehicle-results.aspx?AAIAID=469405