I bought a 2007 HiHy a few weeks back and it had 8400 miles..I just did a free tire rotation at a Goodyear dealer ( free with coupon )...He mentioned he filled in 35 psi on all 4 goodyear integrity 225/65R17 tires which is factory installed tires. Is 35 psi the max for a hybrid?

I dont have the manual handy...should be in there but I thought I will check?

 

Cars don't really have max pressures....tires do. Many hypermilers keep their tire at (or even above(I don't recomend)) max sidewall pressure which is written on the side of your tires. That is usually cold pressure, so you want to check it after the car sits a few hours. Pressures of 40/50psi are not uncommon and they can improve mileage by 10% or more.

 

why is it not good to inflate tires to the max

 

More pressure creates a stiffer tire. That extra stiffness can create more road noise and allow more vibration through the car. In short...a less comfortable ride.

Most performance benefits from higher pressures, but sometime really large contact patches matter. For example, to get out of mud or sand, before steel belts, you could let a lot of pressure out and your tire patch might double in size. Then you have more traction at VERY low speeds. However your tires will be quickly damaged if you drive on them without reinflating.