Tire Width, Tire To Rim, Rim Diameter – This is written like 4. So this wheel is 4. Notice that the size of this tire never specifies the diameter of the entire tire. R18 tires have a diameter of 25. The sidewall of the tire is 3.So your tire size means that the outside to outside widest width of your tire is 4. You can find the recommended tyre pressure for your vehicle in your vehicle handbook or printed either in the sill of the driver’s door or on the inside of the fuel tank flap. Your vehicle manufacturer may suggest different tyre pressures for your front and rear tyres so make sure you’re aware of these guidelines.Ideal Tire Pressure Tire pressure between 32 to 35 PSI is suitable for most vehicles.
What is the 3% rule for tires?
The 3% rule states that when replacing tires, the new tire’s diameter should not differ from the original by more than 3%. This guideline helps maintain proper vehicle performance, safety system functionality, and speedometer accuracy. The performance of tyres deteriorates the more worn they become. In fact the difference in stopping distance between tyres with 4mm or tread and tyres with the legal minimum of 1. That is why it is recommended that they are changed once tread levels reach 3mm or less.It is advisable to have your tyre replaced once it reaches 2mm and the minimum tread depth commonly advised by tyre and safety experts is 3mm. Waiting until the last minute to replace your tyre can prove risky as a significant amount of tread can be worn in just one emergency manoeuvre.