"What is the correct tire pressure for Gen 4 195/65R15 91H" To answer this question, it's necessary to ask first why Toyota recommends 32 psi front & rear when there is a full size spare 195/65R15 91H? My guess is in case of a flat tire, Toyota doesn't want the owner to mismatch the full-sized spare's tire pressure with the other tire at the front or rear, which would possibly be the case if the recommended tire pressures were 36 psi front & 35 psi rear. So, it recommends a uniform tire pressure on all four wheels. Now, the question is: why does Toyota indicate 36 psi front & 35 psi rear when there is no full-sized spare? This is a little bit more complicated. The tire pressure indicated on the inside of the driver's door assumes the weakest tire is installed on the car, which is a tire with a load rating of 89 and a speed rating of S. But the label on the driver's door doesn't indicate the load and speed rating of the tire, only its size. So, in order to avoid contradicting the information on the driver's door, Toyota recommends 36 psi front & 35 psi rear when there is no full-sized spare. In North America, the owners manual indicates there are two "types" of 15" tires: Type A which is rated at 89 S (and has a temporary spare), and Type B (with a full-sized spare) which is rated at 91 H (both types are the same size 195/65R15). For Type A tires, Toyota recommends 36 psi front & 35 psi rear. For Type B tires, it recommends 32 psi front & rear. So, it appears Toyota believes for the 91 H rated tires, the "optimal" tire pressure is 32 psi front & rear, although the 91 H rated tire can be safely operated at 36 psi front & 35 psi rear.