RDC Tyre Pressure Sensor - does rear wheel size matter?

[sleepyfolk]

I was originally going to see if I could code the RDC out, but I thought I'd ask a couple of questions on here first.

I am running aftermarket style 168's - non staggered 275/40/20 all round, I wasn't sure they had the sensors in the wheels until we put the new Michelins on the other week, 2 wheels have what look to be the original sensors and 2 have had replacements fitted by BMW.

My question is: if the sensors were all working, would the system work properly with the non-staggered set up, does everyone running winter tyres just put up with the tyre control inactive for the winter until the 10.5j's go back on.

If it doesn't matter what size rears are on for the aerial to pick up the sensor in the wheel it might be worth me checking to see if one of them is dead and getting the system going again, if it only works with the staggersd wheels I'll code it out for now.

[henrym3]

Bit early for the winter wheels, do you know something the rest of us don't. Is there some mad, wild hurricane on the way
Sorry I can't help with your question.

[sleepyfolk]

[quote="henrym3"]
Bit early for the winter wheels
[/quote]

) , no Henry, I'm just after the theory to see if I can get my RDC working, I'm not sure if my problem is with the rear wheel size or if it's something else, I thought there's plenty of folks on here who have winter wheels on pre-facelift cars, pity they're all so secretive!

[Greydog]

I seem to remember reading that in theory the RDC worked on the rolling circumference of the tyres and used the abs system to monitor.
An under inflated tyre will have a smaller circumference, but then I could be talking rowlocks and have confused with something else entirely.
So as long as you have the same tyres all round and inflated correctly there should be no issue remember odd tyre sizes can cause issues with the transmission some of them very expensive.

[X5Sport]

That is the system on the 6-cyl vehicles.  For some reason the V8s have transmitters in the wheels.  No idea why though.

[sleepyfolk]

Yep, it's transmitters alright, I can't see any reason why with a radio transmitter that the aerial and transmitter would have to be in line vertically but thought I'd ask, maybe I'll have to get it plugged in next and see what it says, I'll keep you posted for future reference

[Greydog]

That must mean mine don't work as from memory all valve stems are standard type !! no warnings or flags so I guess they have been coded out at some time in the past. You live and learn about the devious minds at BMW

Just have to carry on visual check daily and checking pressures weekly then.

[henrym3]

Just from an interest point of view, I don't have the sensors fitted to the wheels/tyres and every 6 months or so I get an OBC warning. By playing with the RDC button and the OBC stalk I can get rid of it. Don't ask what combo I use cos I never remember.

[sleepyfolk]

I'll whizz into my mates garage next week and Plug it in