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[L BISHOP]

I have just bought some michelin pilot sport 3's, but am unsure what tyre pressure to put in the front and rears. The sizes are 225/40/18 92y XL & 255/35/18 94y XL. What do you guys recommend?

[L BISHOP]

Thnaks mate, but I have changed the tyre size from 205/45/18 and 225/40/18 this is the problem.

[miiipilot]

I have wondered also. I switched out the RFTs to Pilot Plus A/S and wondered what pressure was good since the OEM plate on the door is for RFTs.

Same tire pressure applies? They are set where the plate says, however the ride seems kinda harsh and hard (that's what she said!) since the higher temps have arrived.

Anyone else notice?

miiipilot

[Focusedintntions]

If you have your tires filled with normal air, you'll have to adjust your tire pressure at least twice a year. Once when it starts getting hot b/c as we all know hot air expands therefor raising the psi, which in cause gives the harsher ride, so you need to let air out. Then you'll need to add air again in the fall/winter when the air gets cool and the air becomes denser.

If you get your tires filled with nitrogen you'll have to worry about this less as nitrogen is less susceptible for expansion/contraction due to temperature.

[Tom K.]

Originally Posted by miiipilot

I have wondered also. I switched out the RFTs to Pilot Plus A/S and wondered what pressure was good since the OEM plate on the door is for RFTs.

Same tire pressure applies? They are set where the plate says, however the ride seems kinda harsh and hard (that's what she said!) since the higher temps have arrived.

Anyone else notice?

miiipilot

The OEM plate is for tires, be they RFT or GoFlaT. But it's hard to understand why the ride is harsher with your non RFT A/S tires, assuming you inflated them to the recommended pressures.

When I replaced the OEM Goodyear NCT5 RFTs on my ZSP 128i with (GFT)Conti DWS tires, the ride was considerably softer at the 32/35 psi recommended pressures - but steering turn in became somewhat mushy. This was alleviated by increasing the pressures by 3 psi all around.

The OP's problem is that his tires are not within the size range recommended by BMW. I'd agree with TrackRat and start with the recommended pressures for the nearest sized 18" tires and adjust as neccesary for best handling & ride.

Tom

[miiipilot]

I thought since the weather got warmer and the pressure increased to above the recommended tire pressure. Before winter hit, I had it at the dealer to reset the TPMS with the GoFlat tires. Fast forward to a month ago and started noticing the ride was a little firmer (not crashy or anything). I checked the pressure and they were at the OEM plate recommendation.

I was just curious. But thanks for the response.

miiipilot

oh and my tires are 225/255-18 setup