Hello,Sorry for my English in advance.Couple weeks ago i blow the tire on my car and replaced it with a new one, since then my car shaking and i feel bumps more often. I checked my tires pressure and 3 old ones all at 35psi with 40psi max, while the new one was at 50psi with 45psi max (shop work). Being afraid of blowing new tire i let the air out and set it to 45psi like it says on tire. The different between my old 3 and new one tires are still pretty big. On my car door it says that my tire pressure should be 32psi but i beliave its for the stock ones while i got aftermarket 17.My questions are: why my car shakes after i got new tire? should i drop the pressure in new tire to balance them? and if i will, does it gonna effect my tire? should i stick with psi number on tires or the one on the car door?
You should always have 4 of the same matching tires. If your new tire is a different size then you can either get 3 other new tires to match that one or get 1 of the same tires as the other 3. Or one of the old 3 tires could have a broken belt inside of the tire and one of them might be bad also. And you should always keep all the air pressure the same. Normally 32 psi. And it wouldn't hurt to get your tires balanced. And if your tires have an inner or outer wear pattern on the tire you need to get a 4 wheel alignment. Otherwise your tires will go bad quicker.
Changing tire pressure will not affect the balance. Sounds like the tire shop did not balance the new tire properly. The pressure listed on the tire sidewall is the safe maximum pressure. I would determine the actual pressure you want to run by watching the pattern of tire wear closely. Start at 80-90% of the recommended maximum. The mfr sticker in the door is usually a bit low and is based on trying to get the smoothest ride from the tire, not getting the best handling or the longest tire life.
The door sticker is applicable to the stock / factory installed tires only! The panel indicating max load and tire pressure on the upsized aftermarket tire itself takes precedence. Inflate to max psi on a cold tire, and always replace tires in pairs or full sets (if possible), and the new pair should always be installed on the front. The one new tire you put on will perform oddly in relation to the old tire it is mated with due to differences in actual tire diameter, tread design, composition, speed rating, etc., but it shouldn't cause undue shaking. That sounds like a bad spin - balance job. Get that looked into and then you really need to purchase another matching tire.
