Alabama thread!

the trip meter + a percentage based on tire size difference. the rpms of the engine aren't the rpms of the tires.

 

Again, correct.
Just wanted him to know that his trip meter was also affected so it is not accurate either. So since the axle RPMs have been changed you can't really calculate it by just tire size difference.
Like you said GPS and miles used would be best.

 

Your trip meter is no longer giving stock readings

 

but what reading is it giving? what is the trip meter connected to?

 

you have changed your axial speed with the gear so they are not turning the same RPMs as they once were so even if you had stock tires your trip meter will not be right

 

my head is hurting lol. would the trip meter not be tied to the rotation of the tires? a tire can only rotate and travel a certain distance, that cannot change, unless the tire slips/spins.

 

I know motorcycles usually measure tire speed. 4 wheeled vehicles use the drive shaft, right? So his gears do change it.

Either way, just take a trip of known distance, and compare it to trip meter. That's your odometer, mpg, and speedometer correction

 

also new question, my 4runner has 265/70/16s on it.

a coworker is offering me his 2018 SR5 4Runner wheels/tires for 100$ and they are 265/70/17s.

they'll fit right? that's like a minimal difference I don't see why they wouldn't..

 

Colorado elk hunt - link.





Plan to make a run over Bird Camp Road tomorrow - link.

 

yeah being tied to the driveshaft makes no sense to me, if that's what it is. should be on the tires.

 

Wonder if cornering would cause a measurable difference in speed if you measured just one wheel. Also it would be one more thing for people to deal with every time they change a tire. And maybe easier to manipulate/disable to prevent running up the odometer.

 

Happy birthday @TheTacoma !

 

well I mainly meant tie it to the wheel/rim which doesn't change size unless you buy a different size...

 

Lol,
Your odometer cable is connected to your transmission so it measures RPMs at your transmission but your wheel is connected to your rear axle. When you changed gears you changed the ratio between the transmission rpm and the axle rpm.
Your transmisson RPMs are a lot higher now but the axle RPMs is slower. That means less miles traveled than before based on the odometer reading

 

Yeah, now that I think about it, there's got to already be speed sensors on each wheel for ABS. Not sure why they wouldn't use that

 

They should

 

it may pull speed from 3 areas,

the abs sensors attached at the rear axle, right next to the tires.
the transfer case
the transmission

these are my 3 guesses.

 

@stronghammer Found this. Looks like its tied to the driveshaft.

 

yeah that's stupid.

yeah, it's stupid.

yep, that's still stupid.

 

that's in the transfercase not in the driveshaft