With the rapid changes in temperature we experience this time of year it is time to discuss tire temperature and its effect on pressure. Pressure will rise 1 psi for every 10 degrees in temperature. It will also increase by 1 psi for every 5 minutes of driving for the first 20 minutes and hold steady after that if there is no increase in temperature from outside influences such as surface temperature or sun. If you drive a few miles to check your tire pressure it could be off by 1 or 2 psi. More if the outside temperature is high and the sun has warmed up the road surface. A couple of psi doesn’t seem like much but with low profile tires it can be a large percentage of the total volume of the tire with larger tires the effect is less. Gas mileage is affected by tire pressure not a lot but if you combine it with other saving ideas, less weight in trunk, windows up and several others it can add up to quite a savings. There are several sites that explain tire rating so I will not go into it in depth now. Tire ratings are a sliding scale the harder the compound the better it wears, has less traction and a harsher ride. The softer the compound the better the ride and traction but it wears out quicker. I have 3 different tire brands on my vehicles, Toyo, Michelin and Cooper. I have Cooper on my pickup and love them as I do the Toyo on my one Bonneville. The other Bonneville has Michelin and they do ride a bit harsher then I would like but 2 are about in need of replacing. I will probably go with 4 Toyo but I also have a commercial account at the Toyo dealer so the price is less. Tires are another item that every tech has an opinion on such as oil and blondes. But with tires higher price does mean better quality in most cases. Many dealers offer a ride guarantee with new tires also this is another example where having a good relationship with a shop helps.