Need help on tyre size

[deegu]

Greetings from Australia,

I am running 235/50/R18 in the front tyres and 255/45/R18 in the rear. Currently I have the Dunlop SP Sport 01's on my car.

I have my eyes set on some Michelin Pilot Sport PS2s. Been calling around the Michelin dealers around town and unfortunately it seems they have ceased making the PS2 for my tyre size here in Aus :(

One tyre store I called mentioned that although they don't have the tyres in the size I am after, the guy suggested that I try 245/45/R18 in the front :yikes:. As for the rear I couldn't recall what size he recommended, but I am fairly certain that is larger than the roll diameter of my current tyres as well :eek:

To be honest, I have no clue how a slightly larger or smaller roll diameter would affect the ride quality or possibly the life span of the tyres. Can anyone point out what are some of the things I should watch out for if I decide to go ahead with these Michelin PS2s? e.g. Harsher ride quality or uneven tread wear?

Thanks,
Gus

[AzNMpower32]

I don't know if many folks running the 245mm width on the X3 because that's a really unusual size for a tyre in the US (many tires are 235mm or 255mm, but not in between, go figure). The biggest question is whether the wider tyres will fit onto the existing wheels.......this is probably a good question for the Tire Rack section of Bimmerfest.