Let's say someone's left front tire is 43psi and the right front is 42psi--that someone being me. Safety concerns aside, what sort of effect could this potentially have on your mileage? I found my tires to be off by 1-2PSI on each side recently. Obviously I evened them out immediately, but it made me wonder if I could've lost a significant percentage of potential efficiency. Thoughts?
I think there is 1 to 2 pounds of random error in most tire pressure gauges, so you shouldn't expect to get an exact measure that is more precise. Furthermore, your tires will differ by a couple pounds of air pressure if some are in the sunlight and others in the shade. I wouldn't worry about 1 pound difference in tire air pressure.
Not a problem, as mentioned above they change more than that if the sun shines on one side for a while. Radial ply tires don't grow in circumference the way bias ply tires did with increased pressure. Just set them to within a pound of each other in the morning when they are cool and you should be OK. A lot of people are probably driving around with tires that are not within 10 or 15 lbs of each other and don't even know it.
Tumbleweed, The issue with the sun shining on one side for a while is something that I just recently discovered. Since I have purchased a 0-60 psi tire gauge where you can really see the difference in 1 psi I have noticed that the tires on one side read 1-2 psi higher than the other in my driveway. That is when I noticed that the sun hits only one side of the car in the morning. Turned the car around and an hour later the other side read 1-2 psi high. Amazing discovery !! Sorry nooaah, didn't mean to steal your thread !! Dwight
I thought the same thing when I first got the Prius. I took the pressure to 40/38 and thought that was about as hard as I wanted it. Now that the temperature has risen substantially my tire pressure has slowly increased to over 42/40. When I checked it last weekend, I decided to leave it at 42/40 since I had gotten used to it. It is surprising to me how quickly I have gotten used to the higher pressure. I have even raised the pressures in my wife's 2007 Honda Accord to get more wear in the middle of the tire.
I could be wrong, but last week when temps rose from 30s to 60s it felt as if the tires were more comfortable (I always keep them at 39/35 cold presssure). So maybe heat has something to do with the comfort as well - more pliable tires maybe?
You are correct about temperature having an affect on the comfort, especially the first few miles. A cold tire feels a whole lot harder than a hot tire. When I first drive off in the morning, and even in the afternoon, the tires feel really hard. Once the tire gets up to temperature, it feels much better.
