Adjust ODO for new tires?

[ukrkoz]

I have new rubber installed for 2 weeks.
Now, that tires are larger circumference and they cover more distance under same RPM, mpg should go up. No mas.
Is there any way to DIY ODO mpg calculation based on the new tires? Basically, recalibrate it?
07 Tahoe. Stock 20 inch wheels and matching new tires

 

[gooffeyguy]

What size tires do you have?

Only way I've seen to adjust the odo/speedo/trans shifts for different tire size is with a custom tune or an aftermarket tuning device.

 

[ukrkoz]

275/55/20 I believe. Those are stock size, that year had 2 options, 17 and 20. New tires are exect OEM size match, even if my memory gave me wrong number I posted. Tire shop double checked. So ODO is set to that size from the factory, except that for the last few years truck was running on worn out tread, so it's less distance covered by tire at given RPM, than with new tires with full tread.
Sucks. I hoped there's some tinkering that could be done.
What exactly is calculating mpg? Main ECU? BCM? TCM? I could pull consecutive fuses out to reset them.

 

[mb1500]

Not sure what you’re trying to achieve here. Mpg is best calculated by hand.

 

[ukrkoz]

Just peace of mind. It's a bit retarded to go back caveman and calc it by hand, with all the modern electronics built in.

 

[RST Dana]

275/55/20 I believe. Those are stock size, that year had 2 options, 17 and 20. New tires are exect OEM size match, even if my memory gave me wrong number I posted. Tire shop double checked. So ODO is set to that size from the factory, except that for the last few years truck was running on worn out tread, so it's less distance covered by tire at given RPM, than with new tires with full tread.
Sucks. I hoped there's some tinkering that could be done.
What exactly is calculating mpg? Main ECU? BCM? TCM? I could pull consecutive fuses out to reset them.

The mileage is calculated on distance and a guesstimate of fuel used. As long as the tire height is the same as factory, the results will be the same.

 

[gooffeyguy]

I wouldn't think the tread difference between a worn tire and a new tire would effect mpg by anything noticeable. Like maybe 0.5mpg if that.

 

[ukrkoz]

You'll be surprised. Even if it's only few inches - Can't really measure right now but, if I don't forget, I'll measure next weekend, while removing front struts - multiply times say 2000 rpm at HWY speed times yey many hrs of driving... it adds up.
Out of idle knowledge, I had 2 hybrids and, every time I had new tires installed, MPG dropped, in the dash, by about 30% right after. Every time I pulled main ECU fuse and it jumped to better than old tires did.
I'll pull ECM fuses anyway. Just curious.

 

[gooffeyguy]

You can reset/zero the average MPG shown on the DIC by long pressing the check mark button while on that screen.

Mine will very a lot depending on if I'm driving around town or a lot of highway. It's not super accurate, so I don't see how a few more or less revs per mile from the tire tread difference would make much difference.

 

[gooffeyguy]

Just peace of mind. It's a bit retarded to go back caveman and calc it by hand, with all the modern electronics built in.

All these electronics built in are still pretty archaic in a 2007 that's 16 years old and caveman depending on who you talk to. The ECU is just guestimating. To get an accurate milage figure, best to do it old school after a fill-up with fuel used and miles driven.