Ditching runflats - few questions

[dale1uk]

I've managed to persuade my dad to ditch the runflats on his E92 for a full set of Vredestein Sessantas, but he has a few quick questions about doing so.

Obviously there is no spare wheel in the E92s, so he'll be getting some tyre weld to put in the boot incase he does get a flat. What is the best tyre weld to get? Dont want to get one that will be a **** to clean off the inside of the alloy if it does need to be used.

Also, what happens to the pressure sensor if tyre weld is used? Can it be cleaned off or is it new sensor time? If a new sensor is required does anyone know roughly how much a new one costs?

Cheers

 

[dale1uk]

Best bet would be the purchase of the official BMW mobility kit, part number will be from the E90/92 M3. This comes with the can of goo and a compressor which will fit in the boot tidy.

Have looked into the BMW Mobility kits, however £70 seems quite excessive. Are they really worth the price compared to a standard can of tyre weld?

If your father is changing from RFT to non run flats its worth considering that apart from the ride quality improvement and reduced cost, should he wish to trade it back to a BMW dealer they will knock the price of a full set of RFT's off the price offered

Thanks for the heads up, will let him know

 

[dale1uk]

May be wrong but I'm sure I read on tinternet somewhere that the sensor isn't actually a pressure sensor but one that measures the rotation of the wheel and any abnormal change flags up that there may be a puncture.

I'm fairly certain the sensors in the E92 are pressure sensors. It flags up on the dash if any of the tyres drop below a set pressure.

Run-flats are a safety feature that you are removing by putting normal tyres on.

Good point, never looked at it from that angle.

 

[dale1uk]

The sensor is not a pressure sensor its a vibration sensor which is why it can't detect a gradual loss of pressure.

You sure about that?

Just I remember getting in the car when I picked it up from BMW last month after some warranty work and the tyre pressure icon was on the dash. They took it back in and one of the tyre pressures was low so thet sorted it. The service guy said if it drops below a set psi then the icon will show up on the dash.

 

[dale1uk]

That right it does as the sensor detects the change in vibration caused by the drop in pressure. You need to read the manual on them as if you change the pressure you need to be moving to reset the sensors and then they know what each tyre is behaving like, so can detect the changes caused by pressure loss.

If you have something like the Jag XF the values or caps (can't remember which) are pressure sensitive and send a signal to the car about the pressures. They costs a fortune to replace, hence why most tyre pressure sensors are vibration based.

Ah thats great to know, will have a look through the handbook next time I'm up at my folks. Was a little worried about them having pressure sensitive valves hence asking about costs if they failed after using tyre weld