If they talked you into 225/40-18, They sold you the wrong size. You should have 235/40-18. The other size is for GTI and GLIs which are lighter weight cars. The OEM tires may also be XL rated. Pressure is 37PSI. Take your owner's manual with you and show them. The tire size and info is also on the driver's side door frame by the latch. I think Discount Tire gives you a 30 day period to come back and get something else if you are dissatisfied. The tire size error is theirs. They have the right info on their website. I never had the Pirellis as they were only offered in 18" and I have 17" so I can't vouch for tire wear. I certainly wouldn't skimp on the tires whether you are keeping the car or not. Again with the batteries, that is a maintenance item and would get replaced sooner than later. You live in Houston and the heat takes a bigger toll on things.