Funny thing about the tire pressure marked on the sidewalls.... Even when my (previous) car had stock tires, the numbers never matched between tire and data plate.

isn't the information on the tire MAX PSI? Which isn't necessarily what you want to inflate them to. The markings on the data plate are the recommendations for the application, based on the weights of the vehicle and its recommended loads.

That's one of the reasons why the numbers didn't match in my case. The car recommended different pressures for rear versus front tires. All four tires were the same brand/model and all had identical markings - all higher than what was printed on he data plate by about 25%. Tire says "44 psi" and car recommends 33.