tubbee

Hi guys,

Got another question here about Run Flat tyres, are the rims used different from normal or heavier?

Also, are style 124 Run Flat rims?

Thanks for the help.

Eric

555

Run flat rims?? What's that? The car comes with run flat tires. I thought the rims are just the regular type.

silver4evr

The tires are "run-flats", not the rims.

btw, the FTM (flat tire monitor) works off of the the tire rotation speed of each tire and compares each tire to to the others. If one tire rotates significantly slower than the others, the systems registers a flat. Lower air pressure in a tire creates more friction and the more friction the slower the tire spins.

I was advised by the dealer today to check the air pressure at minimum every two weeks and intialize the FTM in the i-drive.

I had been checking the air pressure regularly with the standard air pressure gauge but its not accurate enough. I will be getting a digital air pressure gauge to insure the tire pressures are much more accurate. This will eliminate the FTM warnigs I had been getting.

Guest_Stu

HI Silver4EVR. " more friction and the slower the tyre spins".... Not quite how it works.
When you get a flat the rolling radius reduces.
Remember the old Pi times D = circumference?
Well the flat tyre then rotates more quickly than the others . ( though you are correct it has more friction)
The sensors used in the ABS system pick this fact up and activate the tyre pressure monitor.

Now just my opinion.. The 124 style wheels really set the car off. I gave up any nav option just so I could afford them!
Apparently the aftermarket "copies" have solid spokes and weigh more.
The run flat tyres do weigh noticably more than the std tyres , add this fact to the stiffer ( thicker and stronger ) sidewall and you have the explanation for the rougher ride.

When my girlfriend first drove the car she was disappointed with the harshness of the ride ( esp on crummy uk roads).
However it's nice to know that if she is driving at 100mph ( or more ) , with our baby in the back and she experiences a flat or blow out then the car is perfectly driveable.
I also love the fact that she will never have to wait for the AA RAC or change a flat in the rain or a dark and dangerous neighbourhood

pbarch1

I thought I had a FTM issue a few weeks ago, Every time the monitor went off I stoped and checked the tire pressure and inspect the tires. I went as far as to bring it up with my dealer only to find out that I did in fact have a nail in one of the tires. While it was troublesome to stop and continully check the tires it was also conforting to know that the system really worked.