Runfat tyres on an NC

[IanC]

I purchased a second hand NC Roadster a few weeks ago . Great car! It replaces an NB and I’m astounded at the difference the extra 200cc makes. (Quick plug- see the for cars for sale: [ACT] NB, 2003 model)

Anyhoo, the previous owner, proper gentleman that he is, had runflat Potenzas fitted to the car coz his wife used to drive it 150k or so to and from work each day and he didn’t want her having to be fiddling around with a can of goo and a compressor on the side of the road if she got a flat. (There is a question buried in here, trust me!)

Now given that this is the first NC I’ve owned, I have nothing to compare the runflats to and although a tad noisy, they seem to provide reasonably adequate grip but having said that, I don’t have to try too hard to get that little orange, DSC light a flashing. (That question’s coming along any minute now!)
The problem is that cars that are fitted with runflat tyres are also fitted with a Tyre Pressure Monitoring System (TPMS) and of course the NC doesn’t have a TPMS. In fact, I’ve heard a nasty rumour that runflats should only be fitted to cars that have a TPMS. (It’ll be along soon now.)

As I understand it, in the event of a puncture in a runflat, speed should be limited to 80 kph and the tyre can only be dríven on for a max of 200k. A mate has a BMW fitted with runflats and when he had a puncture in one, the only reason he knew that it was flat was when the Beemers TPMS alarmed.

(So here it is! Finally!) Without a TPMS, how do you know if you have a puncture in a runflat? How do you know that you have to drop the speed to 80K and that you should zero the trip meter and hope you make it to the tyre shop before it clicks over 200k? Does anyone have an experience with this?

And since I’m finally in the question asking mood, have any other NC owners tried runflats and if so what’s your experience with them? And, since I have them on the car and the Potenzas have probably got at least six months life left in them, has anyone had any experience with the Tyredog TPMS Wireless Tire Pressure Monitoring System that’s available on eBay for $169.00?

Appreciate your assistance.

[NitroDann]

The power is 20 years of technology, not 200cc of capacity.

Dann

[Guran]

I used to own a MINI Cooper S and then until very recently a BMW 135i Coupe. Both came standard with runflats. Sorry ... runcraps! Horrible bloody things. They totally spoil the ride quality. I swapped over to regular tyres, saved some cash (runflats are usually more expensive), and enjoyed improved ride (still pretty ordinary in both cars).

You cannot tell by looking at them if a runflat tyre has reduced pressure. You only stand a chance of seeing it when dead flat. Running on a deflated runflat for prolonged time at normal speeds will damage the tyre. That's why you need tyre pressure sensors. I believe the stock ones work off the ABS system by detecting the slightly smaller diameter (ie. angular velocity) of the deflated tyre. If you're going to use runflats, you should definitely get yourself a TPMS.

One last thing, you should do some research to make sure the wheels you're using are compatible with runflat tyres. I understand NCs were supplied OEM with runflats in some markets (not Australia), so maybe the stock wheels are OK? The problem is that runflat tyres require a different design on the rim which means that runflats should only be fitted to runflat-compatible wheels. On the other hand, normal tyres can be used on wheels designed to take runflats.

Suggest you have a read of the following links:
http://en.wikipedia.org/wiki/Tire-press ... ing_system
http://www.performanceplustire.com/tech ... tems-(tpms)

[bruce]

Runfat, hee hee!

[93_Clubman]

Slowpoke from the ACT did some research on runflats & other technology to get around the lack of a spare on the NC - perhaps he'll chip in, but you could PM him as I'm sure he'd be happy to elaborate.

[Muzdaman]

Only get the TPMS if you plan on keeping run flats.

Personally I would use them up over the next 6 months then get real tyres.

[IanC]

Thanx folks for your comments and suggestions.

I’ve dropped Slowpoke a PM but in the meantime I’ve also purchased a TPMS on ebay for $165. It seems to me that the sooner you get a heads-up that there’s a drop in pressure in a tyre, the sooner you can stop and have a squiz. The alternative is that you fail to realise that you have a problem, continue to drive on it and run the risk of destroying the tyre and possibly even the rim as well. And it seems to me that low profile tyres coupled with lots of 100kph plus highway driving leave little room for error!

Just in case others are interested I’ll try to remember to post my experiences with the TPMS after I’ve had it for a while.

Thanx again.