hope this is posted in the right section if not I apologize. Question is the door tag says 30 psi. My brand new cooper discoverer at3 don't like that. They have a slight bulge out at the bottom of side wall like they are under inflated. I put in 35psi it looks great and nice and straight. Is there anyway I can program the tpms to think 35psi is 30? Thanks
What's wrong with a bulge? This is a characteristic of radial tires- always has been since their implementation in the 50s.
Also, that label was made assuming the truck has stock or stock-equivalent tires. A different size or make (more plies/"LT" designation) of tire may require more or less pressure. The point of a specified tire size, type and pressure is to maximize the contact patch and load stability. It is determined by the vehicle manufacturer after thorough testing with the vehicle's weight and handling characteristics. If the tire is different enough than stock spec, then that label is essentially irrelevant and you'll have to determine your ideal pressures. Too low of pressure causes more of the vehicle's weight is on the shoulders (outer edges) of the tread so that wears faster. Too much pressure and the center wears faster. Generally, if enough air is in the tire to have no bulge, then it's over-inflated and the contact patch is smaller. This will cause uneven tread wear, a firmer ride and less grip. Again, all of these dynamics are dependent upon what tire is used as compared to the OE spec'ed tire.
Now, if 35 happens to be a good (safe) psi, then roll with it. Last I knew, you could have the system reprogrammed with a TechII. But, as Nate said, 5psi over shouldn't trigger a warning. Perhaps your gauge reads low and you're putting in much more than 35psi?
