Gas station air and Firestone

So last week, my wife's 2010 Prius tire pressure alarm lit up and the passenger-side, rear tire was down to mid-30s. I dropped it off at Firestone at lunch and took the 03 Prius back to work. That evening, I paid for the repair and the clerk said they'd found the other three tires were at 50 psi so 'We adjusted all of them to 35 psi.' As if I might not have known.

I nodded my head in resignation and said, 'No problem, I'll fix them.'

With some relief that I would re-inflate the tires, he asked, 'Why do you run such high pressure?'

'Better fuel economy,' and drove home to get the dogs and walk them back to pickup my wife's car. I was not going to argue with with him as the 35 psi (car door pressure) is policy at Firestone and this local franchise has to follow policy.



Well I had left the electric tire pump in the other car (note to self, pickup another at the next Harbor Freight sale) and the dogs and I had to run some errands. So I picked up the tire pump from the other car and run errands:

• 'Where did that extra tire noise come from?' . . . oh yea, lower pressure tires.
• 'Hummm, why is the car steering dead and imprecise?' . . . oh yea, lower pressure tires which also reduces tire alignment errors that tire stores sell as a service:
• I remembered my tire temperature tests:

Later that night in the empty, work parking lot, I let the dogs run while I started filling the tires. It takes about a few minutes per tire and I was pleased to avoid paying $2 to do the same at a gas station . . . if their machine was working. I was thinking:

• The best way to improve vehicle mileage would be free air at each gas pump, something I remember from the 1970s. But the oil companies know low tire pressure reduces fuel economy and they sell more fuel.
• Firestone follows the door sticker pressure but lowering a customer's tire pressures also means higher tire wear and they sell more tires. Sure, they are just following the car maker's recommendation.
• Lower tire pressure provides a secondary shock absorber so the car makers don't have to build a better suspension that handles the tire-shock function.
• Having the tires at 51 psi (maximum sidewall,) means a slow leak brought the tire down to the door sticker pressure.

Gas stations ended free air which reduces their gas sales. Tire stores treats the door sticker as both a minimum and sad to say, maximum, and by policy lower tire pressures without asking the owner before acting like the screw they removed, and letting the air out. The lower tire pressure wears them out sooner from heat; makes tire alignment more effective and; they sell more tires and service. Finally, the car makers build simpler suspensions instead of running higher pressure tires and a better quality suspension.

Bob Wilson

ps. Here are the results of my tire study that led to oversized, front tires, a permanent 'over-drive.'