Car Myth Busters #22: Fill tires to maximum sidewall PSI By Frank-Ling / Mar 06, 2014 share Facebook Twitter Google + LinkedIn Pinterest Email Share... By Frank LingIf you talk to 5 different people about what their advice is on the proper pressure for tires should be, you’ll probably get a mixture of answers from over inflating to under inflating them.Some will say just follow the tire manual specs, while others believe that you should inflate the tires to the maximum pressure according to the tire sidewall PSI numbers.So if you want your tires to last longer with optimal performance, what is the best course of action to follow?The numbers gameWhen tire manufacturers give their recommendations on what the proper pressures should be for their tires, these numbers are used to reflect cold tire pressure because the temperature of the tire affects its internal PSI (pounds per square inch).Hot tires will register a higher PSI then cold tires, so to set some sort of standard, the recommended tire pressures are always for cold tires.Over or under?The sidewalls of tires have information set in raised letters and numbers which show its size, the speed rating of the tire, load capacity, and the maximum PSI the tire can be inflated to.But this sidewall listing doesn’t mean that you should inflate the tire to these maximum numbers. It is merely information as to how much maximum pressure the tire can take.Some suggest that over inflating a tire gives better performance and handling, but this practice will also speed up tire wear, give a harsher ride, and could potentially be dangerous and cause a blowout.Under inflating tires can help to give a smoother or cushier ride, but again, the tires will be more prone to wearing out more quickly, while handling will also be degraded.Stay with the manualTire companies spend many millions of dollars in research and development and note what the optimal tire pressures should be for each of their products for maximum tread wear and handling.When in doubt, check with the tire manual for the proper PSI, look at the sticker that is placed at the end of the driver’s door, or visit the tire manufacturer’s website for the proper PSI for your tires.Source: Kaltire.com