E61 runflats to standard - puncture indicator

[istoo]

As above, i changed from the standard NCT eagle runflats to falken 452's last month.
We did get the "you have a puncture" indicator once ever month or so with the old tyres, say a bulge on the inside of the front nearside tyres which i assumed was the problem. worn rears as well last month so bought 452s and have them professionally fitted and balanced. Does it ride better i find it hard to tell to be honest, ended up with 2psi more in the fronts to make the feel right.

However every few days the "you have a puncture" warnign keeps flagging up, i have a dead accurate digital guage which shows no loss of pressure. can someone point me in the right direction here? Does this gauge work from sensors in the tyre?

[phumy]

istoo, i believe it works from the abs sensors, it look at the rotational speed of all the wheels, hence if you have a puncture in one it will see that one tyre is rotating quicker that the others and flag it up as a puncture. So it could be a tyre pressure problem or a sensor problem....

[phelix]

Try resetting the system via the idrive - that should cure it. If you had an ABS sensor issue you would see other errors - the different rolling diameters front and rear have probably misled the system into thinking you had a puncture.

[istoo]

oh it gets reset through the idrive 1-2 times a week, so its not right there. It has 4 brand new tyres so i doubt its that either as it was doing it prior. and yes they are the correct circumference as well.

Thanks phumy thats what I was looking for, should the diagnostics pick up a faulty sensor? is there one sensor per wheel?

[MazDave]

When I had the same issue on my E61 it turned out to be a cracked rim, hardly noticeable drop when checked on the tyre pressure gauge but it was bringing on the bonger. Managed to find a tyre place with a big enough water trough to check and it bubbled up on the inside of the rim near the root of one spoke.

Assuming it's not that - I'm lead to believe that the dealers can alter the sensitivity of the System - that might be a myth though.

I did find that my 05 plate car was much flakier on this than my 07 which has been good as gold (touches wood)

Best of luck.

Dave

[phumy]

Yes there is one sensor per wheel, a requirement for ABS and TCS, all these systems are so well integrated nowadays. Do you have the same tyre sizes on now that were on before you changed them?

If you have a different aspect ratio on the front to rears that could throw the system out.

[istoo]

Will nip to the garage and see if they will run the diagnostics machine see what she says, i wonder if the bonger can identify which wheel is at fault. I kept all the tyre details the exactly the same as the factory setup.

Will have a good old double check on the rims, its a 55 plate car they look in good condition, one thing i did consider is not a crack but maybe a flatspot on the rim? They arent loosing any pressure at all, my digital gauge measures to 0.1 of a psi. And its dead solid +/- .1 psi for warm/ freezing weather.