Dear Car Talk:
My son's car is a 2010 Camaro. It has Pirelli all-season tires on it. The sidewalls of the tires say 50 psi, but the service tech said to put in only 35 psi. Who's right? We put in 35 psi, and the car rode rough. We put back in 50 psi, and my son says the car rides better. The 50 psi seems like an awful lot of air. But it's on the side of the tire. What's the right answer?
You might have a medical situation on your hands, Larry. If your son thinks the car rides better with 50 pounds of air in each tire, I'd rush him right over to the nearest 24-hour tuchus specialist to make sure he still has sensation in both butt cheeks.
Fifty psi is a lot of pressure for a passenger-car tire. That number is on the sidewall because it's the tire's maximum allowable pressure. That means you can put up to 50 pounds of air in that tire without worrying about the tire exploding or deforming to the point where the car won't handle safely.
But the maximum pressure -- that number on the sidewall -- is not the same as the recommended tire pressure. And that's the number you're looking for.
You'll usually find the recommended pressure on a sticker inside of the driver's door pillar. That number probably is closer to 30 or 35 psi. That's the pressure at which the manufacturer believes the tires provide the best balance of handling and comfort. And that's what I'd use.
Driving with 50 psi in your tires is like driving on four round boulders. You'll feel every piece of chewed gum that someone else has tossed out his window. The tradeoff is that you'll get slightly better mileage. But for most people, trading off so much comfort for a little more fuel economy is not worth it.
But if he likes it at 50 psi, he's free to drive with 50 psi; it's probably not unsafe. Plus, with his head banging on the roof over all those bumps, he'll never fall asleep at the wheel!