Wednesday, September 14, 2011

Why do the auto mechanics overinflate my tires?

I read in my owner's manual (for a 1995 Saturn SL2) that it is very bad to overinflate or underinflate the tires, and that you should only inflate them at the recommended pressure written on a label on the driver's door (add 4 PSI if they are hot). The last two times I had repairs done on my car (the first one was for a thermostat change; the second one was for a brake job), the auto mechanics inflated my tire at 34 PSI (cold). But my car label says to inflate the front tires at 30 PSI and the rear tires at 26 PSI. So why don't the auto mechanics follow the car label recommendations? Is it because my owner's manual is misleading? Or is it because they are too ignorant? This would be scary, as it seems to me that tire pressure should be fundamental knowledge on a car. How can I trust them then when they say that my fuel filter needs to be changed if they don't even know that overflating tires cause them to wear out more quickly (e.g. see http://www.aa1car.com/library/2003/ic100368.htm )Why do the auto mechanics overinflate my tires?
The plaque or sticker on your door is from the auto makers they know how much air gives you the most comfortable ride for the tpye of vehicle you have. The tire can handle more air but the automakers want the car to ride its best when you buy it. Some people like more air because you get better gas mileage. I've contacted many tire sales shops and they all give different awnsers. My best suggestion is to go with what feels best i the ride you get. If you want a softer ride go by the door sticker if you want better gas mileage then pu 34 or 35 in them. It has nothing to do with anything but the ride you get and how you like it. Having your tires at 35 or 30 is not going to make that much difference in the wear of your tires as long as you get them rotated every 6k.Why do the auto mechanics overinflate my tires?
So YOU can lower the pressure to make all equal with use of a compressor.Why do the auto mechanics overinflate my tires?
Manufactures recommended tire pressure is just a suggestion in my opinion. Some tires will wear the outside of the tire if inflated to manufactures spec in which case if you would overinflate you can get more life from the tire. Overinflating makes the tire wear more in the middle of the tire. Of course, there is a cut off on how much to overinflate. I don't like to go about 5 psi. This is done all the time and I do it on my own car. Don't sweat it but, if you want to, keep an eye how your tires are wearing. They should wear evenly the whole way across.Why do the auto mechanics overinflate my tires?
You should follow the car manufacturers recomendation if you want a ride. If you want tire wear and handling, It would be best to follow the tire manufacturers recomendation on the sidewall of the tire. The tire manufacturers should know best how to inflate thier brand of tire. I have advised many people how to keep thier tires inflated. They should be inflated to the tire manufacturers specs. You should not have abnormal wear or bad handling following thier directions. If you have abnormal wear following the tire manufacturers recomendations, you may possibly have an alignment problem. In that case you should follow the car manufacturers recomendation on the alignment specs. ie; are you going to let the tire manufacturer tell you how to align the car??Why do the auto mechanics overinflate my tires?
I have found that the maufacturers tire pressures are a bit low.Sure the ride is softer but I like the feel of my car a bit tighter so I go over by 3 to 5 psiWhy do the auto mechanics overinflate my tires?
Usually the mechanic will set it to the tire's max inflation if they can't find a chart on the door handy.



The manufacturer came up with it's recomendations as the best %26quot;overall%26quot; pressure to inflate it... For ride,for wear , for traction etc.



inflating it 4 psi won't affect it at all other than giving a almost unnoticeable harsher ride....



The underinflation/overinflation is people who never check pressures (and the tire is at 10-15psi like so many that had tires fail a few years ago) or people inflate as the article says till they look full (which usually is 60psi..too much for a tire to take normally without blowing up when it got hot and starts expanding)



4 psi won't kill you or the tires. they will wear a hair more if overinflated,up to a 1/32 difference, but that is usually for tires where the manufacturer recommends say 30 psi and the person inflates it to tire max of 44psi (as some tires allow for)Why do the auto mechanics overinflate my tires?
I seem to remember something about tires not at the right psi causing you to use more gas/cut down on your miles per gallon.Why do the auto mechanics overinflate my tires?
The recommendation if for the tires that came on your car. Your car is 11 years old, my guess is that you have different tires on it. Look at the sidewall of the tire, what is the recommended pressure?Why do the auto mechanics overinflate my tires?
There could be a few factors at play here. 1. Your guage might read slightly different than your mechanics. 2. If your tires are at a little higher pressure than they are suppose to be it is actually a good thing. It makes the car handle better and also improves your gas mileage by reducing the tires rolling resistance. 3. Most tires say right on them to inflate to 32 PSI I don't know what kind of tires came stock on your car but they are probably not the ones that the manufacturer put the specs on the car for.

If I were you I would ask the mechanic to explain to you why he is putting more air in your tires and I bet he will be more than happy to tell you. If you ask him to stop doing it he most likely will. If he checked your tire pressure for you while he was changing the thermostat he probably was just trying to help you out so that you will come back for any repairs that you might need in the future. It sounds to me like you have a mechanic that cares about your business. Just some food for thought. Hope I have been helpful

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