Originally Posted by markrivers

Hi guys!

i got a little bit bored this 3 day weekend,
so i have decided to do what my " Prius" friends are doing with their cars. Hypermile.

Basically, they put a lot of air on their Low Rolling Resistance Tires for better mpgs.
most do 45, while i know some who puts 60psi.

Hmm.. so let's test that on a 2013 RX 350 running on regular unleaded 87 octane ( Costco gas) with OEM tires ( Dunlop Grandtek) and 19 inch rims.
every gauge was reset to ZERO
trip A
average mpg
average speed

here's my baseline: i do 85% highway and 15 % city driving.



and here's what happened after putting 38psi ( too scared to do 40)



and nearing the end of my commute



and at here's the final



Disclaimer: i don't recommend this practice at all.
Overinflating the tires can give you a lot of mpgs but it can be unsafe
Although, aside from a bumpier ride, i didn't feel any difference in the drive.

Originally Posted by fastnoypi

The max inflation on the sidewall is a safety max at cold tire pressure prior to bursting concerns that can be caused by bumps and road hazards once the tire air warms up.

Exceeding past the manufacturer's max load cold tire pressure recommendation will lead to a smaller contact patch with excessive wear in the center of your tire . It will affect handling characteristics and braking distance which is unsafe. You're compounding the risk of a blowout being in a heavy SUV.

Not worth the risk to the safety of yourself, passengers and others on the road, just to save on a few gallons of gas IMO.