Is 42/40 trading tire life for MPG?

This is true if and only if the tire supports significantly more mass than the vehicle on which it is mounted and is more reflective of "old school" mentality. Generally, this occurs only if you have much larger tires than stock, or if you have a "performance" version of specific model that provides much larger (wider) tires than the base car. In my experience, this has very rarely occurred such that tire life is adversely affected with increased pressures. Tires provided are typically often very close in weight rating to the weight of the vehicle. As a result, more often than not, factory specs tend to underinflate the tires. Increasing pressure, as previously reported, will often decrease ride comfort and increase road noise while reducing sidewall rollover during cornering (wears outer portion of tire) and evening out the contact patch. Plus you will see 2 - 5% increased fuel economy.

Lastly, keep in mind the intent of the tire placard pressures - overall ride and handling compromise. Most manufacturers set this pressure 4 psi below what is ideal for the tires to improve road noise and reduce ride harshness from pavement expansion joints, etc. I think there is enough miles and thus data to prove the higher pressures have not adversely affected the tires on the Prius.

 

Not to change the subject but still about tires. Does anyone have more information about trading OEM tires for the Comfortreds. How does a person go about exchanging.

Thanks

 

I'm at 42/40 right now for tire pressure. Tires look new after 22K miles. I rotate every 5K mile (as well as oil change). I had them at 44/42, but summer temps seemed to inflate them too much. Now at 42/40 I feel I have a little 'safety factor' to the maximum 44 PSI. I've done great so far in the traction department (although snow has been few and far between this winter!). The ride/comfort level is 'not soft', but not 'harsh' on my butt or the car. Kinda subjective, coming from a CJ Jeep, and an old Pathfinder 4WD. I'm just glad the tires are doing better than the classics (which, sadly, is the only reason I've 2 sets of relatives whom gave up on their classic(s), but now have to be kicking themselves after seeing my new version doing so well.) Not nice to gloat, but, hey, the Prius made me do it!