Wat is ur tyre size now? u can see it at the side walls of your tyre. Eg. 185/55r16
Then use the tyre size calculator to check similar sizes:
http://tire-size-conversion.com/tyre-size-calculator/General rule is do not exceed 3% error.
Some people say u can lowering the tyre pressure to get extra comfort. But there are also cons.
http://outbackjoe.com/macho-divertissement...pressure-guide/Best is to follow the recommended tyre pressure.
Tyre pressure is not determine by the tyre size. So if u change a different tyre size, it will not affect the tyre pressure.
Tyre pressure is actually determine by:
1) Car speed (normally how fast u drive. U can follow the tyre recommendation sticker. U will see it when u open the car door.
2) Car load (If u are bringing alot of passengers or stuff, u may need to increase tyre pressure)
3) Duration (If u are bringing heavy load for a long period of time, u may also need to increase tyre pressure)
Always invest on a good tyre pressure gauge to check the tyre pressure every 2 weeks or at least once a month.
PS: i read mostly from internet and forums so correct me if i am wrong, hehe..
There is a sticker near the driver door that state the pressure. Curious is the pressure is for HOT or COLD tyre?