2018 Ford F-150 - How far?

Dear Car Talk:
I own a 2018 Ford F-150 and a 2018 Chevy Equinox, both with the original tires. When I drive my truck from my home to the interstate on ramp it is exactly 40 miles. However when I drive the Equinox the odometer reads 40.7 miles. What gives?

Someone is worrying about a non-problem . Do you realize that these are not NASA grade instruments or are you just Trolling ?

1 Like

The Equinox has a shorter wheel base, therefore has to travel further?

1 Like

Worrying about a 1.75 % COMBINED error in the odometers in your 2 cars is like worrying about the amount of fly poop in your burrito.

I got you thinking about fly poop in your burrito, now, didn’t I. Can’t get that out of your head now. At least you will stop worrying about odometer error.


Some of us read that while eating breakfast ( fortunately not a burrito):roll_eyes:

1 Like

One of them is closer to being correct than the other, The real question is which one?

1 Like

Time to load up a GPS app and find out what a ‘better’ estimate is. Now you’ll have three numbers!


Odometer/speed odometer readings change as tires wear down.The only true test would be to have brand new (OEM size) tires on each vehicle and run the test again. Even then they may not be exact. There’s probably a manufacturing tolerance of ± 2%.

1 Like

Back in the 70’s, when I read car magazines regularly, +/-5% was common even on a new car.


A man with one watch always knows what time it is. A man with two watches never knows.


Unless both are in sync with a known accurate source

Since a tire’s circumference changes every time you drive the car due to tire wear, there’s at most once in the tire’s entire lifetime the odometer is perfectly accurate.

While that is true…after one time of driving the car on new tires you’d never be able to measure the circumference difference without using an extremely precise instrument that can measure down to 5 decimal places.

There’s also tire pressure change with temperature, which changes rolling circumference.

1 Like

All speedometers are off a bit. We had a guy bring a Subaru in once wanting a new speedo because a cop in a small hick town had ticketed him for doing 47 in a 45. I showed him the factory service manual which specified a 1.7 MPH error at 45 and a 2 MPH error at 60.

I told him he was just being yanked by a revenue generator and a new speedometer would make 0 difference. I did give him a printout in case he decided to go to court on it.

Today I discovered I am the man with one watch who never knows what time it is. I started wearing my grandfather’s watch last week. Mostly it’s great. Sometimes it is suddenly 10 minutes slow, sometimes it just stops. If I get a second watch and it is reliable, I will become the man with two watches who always knows what time it is.

I dunno, you’re driving a Ford and a Chevy- consider that they might both be wrong.

That, or you are parking your Equinox on the other side of your .7 mile wide garage.

I have an indoor-outdoor thermometer with a satellite controlled clock that claims to be accurate within a few seconds. It is, if you consider 180 a few.

Only a man with a broken watch has one that is exactly right twice a day.

1 Like

One reads 40 the other 40.7 - that’s a difference of 0.35 each. Or 0.87%. Are you serious?
Over 100,000 miles that’s only 870 miles.

It’s gonna bug you even more when I tell you the speedo & the odo in a vehicle are not necessarily calibrated exactly the same either.