View Single Post
Old 03-10-2010, 12:43 AM   #76 (permalink)
roflwaffle
Master EcoModder
 
roflwaffle's Avatar
 
Join Date: Dec 2007
Location: Southern California
Posts: 1,490

Camryaro - '92 Toyota Camry LE V6
90 day: 31.12 mpg (US)

Red - '00 Honda Insight

Prius - '05 Toyota Prius

3 - '18 Tesla Model 3
90 day: 152.47 mpg (US)
Thanks: 349
Thanked 122 Times in 80 Posts
Quote:
Originally Posted by Big Dave View Post
I've talked to literally hundreds of truck guys. Bigger diameter tires actually reduce MPG.

The reason is increased rotational moment of inertia. RMOI goes up with the square of the radius. Big tires are OK if you go long distances at a constant speed, never slowing down or speeding up.

I don't drive that way.
Even w/ large tires RMOI is quite small for most vehicles, something like 10Wh/mile assuming a 0-60-0 every mile. Odds are it's an increase Crr/CdA associated w/ the larger tires.
  Reply With Quote