Thread: 18" Tyres V 19" Tyres

Originally Posted by discojools

Robert,
Yes you're right the professionals have no idea.. The bloke who sold me the 245s told me when I first enquired that 5% over standard was allowed in Vic. Also they seem obsessed with putting much higher pressures (40-45psi) in the tyres saying that "Oh yes you'll get much better mileage and mpg out of the tyres". The grip levels are much less especially in the wet as I found out when nearly crashing my old Rangy when I picked it up from service where they had overinflated the tyres.

Where does this 5% rule come from...I have no idea and neither do these tyre 'pros'.

Anyway 40psi for many vehicles is fine (all advanced driving schools I know advocate higer pressures than normal), I run that on my D3. He is correct btw to say mileage is improved and wet-weather grip is also improved. However, go too far on the pressure and grip levels drop and the tyre can be damaged. I once had a tyre shop put 50psi in my Pajero's tyres, just because they could....