New Tires - Gas Milage Decline!?

You will need account for the 31" to 32" tire diameter increase, as the odometer will be off. If your dash is showing 17-18 mpg, you're actually getting 18-19 mpg.

You should also know Toyota's selection method for picking OEM tires:
1. Lowest bidder.
2. Best mpgs.
3. Enough pavement grip to pass gov't handling tests.

^Note all-weather performance and off-road performance aren't considerations.

So it shouldn't be a surprise that any tire you buy other than the OEM tire will result in a slight fuel economy hit.

 

This is ABSOLUTELY incorrect. Heavier tires have more rotational mass and require more energy to get and keep them spinning. This is basic physics.

 

I put skinny tires, a.k.a. "pizza cutters", (235/85/16) load range E on my 2020 TRD Off-Road. They weigh about 10lbs per tire more than the stock tires and are a 32" diameter tire. I also run the new tires around 50 psi, which helps the gas mileage (at least a tiny bit).
Before I added them, I had already built out my truck and added weight and a 3" lift. All the original adds cost me about 1mpg but once I changed the tires I lost another 2mpg. Now I am down in the 16.5 to 17.0 mpg range.
Was getting 19.5 to 20mpg with no mods.

 

Yup, your MPG won't be accurate. trucks computer is calculating for a different diameter tire. In my 4runner, I had issues with ABS being way too sensitive and I think this is because the computer was calculating for a different sized tire.

So there's 2 things going on, you have a tire that itself will reduce gas mileage and also your computer is tweaking.

 

Here's the real question here how big is you sample size? One quick trip? 1 tank 6 tanks? My mileage varies day to day 20L/100km one day 12L/100km the next conditions, route how much water the station owner decided to dump in the holding tanks that week....

Every mod you do outside of factory spec will affect the performance, as stated bigger size more weight more resistance therefore more work to move. The one thing I didn't see was what spec of tire went on P, C, E? That will greatly alter the tire weight.

I stuck on new wheels and one size up duratracs on hardly noticed a difference but they were P rated tires super thin and light With much less tread depth.

 

guess you missed that thread. Sorry, it was a riot