I understand that the principle behind runflats is that you can drive some distance "at a reduced speed" on a flat (or pretty much deflated) tire. This supposedly can be done without damaging the wheel. But, what about the tire? If I do actually have to run flat on my runflats, will the tire be toast?

I guess why I'm asking is that I've never been a fan of the runflats, and am seriously considering switching to a conventional tire when these wear out. I simply do not see the advantages of runflats over conventional backed up by a can of fix-a-flat and/or roadside assistance. Especially if by running flat I end up destroying a $200 tire. I'd much rather destroy a tire that costs 1/2 that much. Besides, the runflats seem to be responsible for handling that is harsher than need be (i.e., they accentuate the harshness of the already stiff sport suspension).

What do others say about this?

 

jsun: from what I gather (I'm no authority by any means) the tire would be dead after the 50 miles. The heat build up alone would probably have degraded the rubber. As it is, even without driving on an uninflated tire, some of the run-flat manufacturures claim you shouldn't patch the tire anyway.

For general use, I have been using non run-flat tires (Yokohama AVS ES100s) and then carrying the following:

- cellphone and roadside assistance card: my first option is to call for a tow, since I don't want to gunk up the wheel if I don't have to.
- fix-a-flat and a compressor: my second option, to get me off the side of the road if I had to.

Maybe Dan or someone else can comment further.

 

Not that it makes a difference, but I don't believe the problem would be heat buildup. As I envision it, the wear on the tire is due the change in loading profile when you go from a fully pressurized tire (with fairly even load distribution on the tire walls) to an un-pressurized tire that now is taking the fully weight on the sidewalls. So, it would like the wheel riding on two stiff rubber disks. Eventually, the stress will weaken the disks and they will lose their rigidity.

I guess blowouts are possible, but the worst scenerio I can imagine in using a run-flat that has been driven on is that eventually the sidewall will not support the weight, and it will eventually not be able to be driven on without damaging the wheel. It would seem to me that you could repair several leaks before that happens.

I am hoping that someone will eventually come up with a good solution that does not count on road-side service and fix-a-flat. First of all, cell phones do not work everywhere. Secondly, some tire damage can not be repaired with fix-a-flat. Is anyone with a MCS carrying around a MINI donut-spare with them? If so, how much room does it take up? Has anyone though of a clever mounting location?

 

Run-flats have stiffened side walls that allow you to drive them even with no tire pressure. While the maximum distance is 50 miles, that is for a completely flat tire. The distance you can drive with a run-flat that has some air in it, say 15psi, dramaticaly increases.(Not that I am proud of it, but I have driven over a hundred miles with a run-flat with only 10psi in it and the tire was just fine.) Driving 50 miles on a run-flat tire that has no air in no way comprimises that tire. This technology has been around for over 5 years now.

Run-flats may be patched. Slow leaks are more common than total flats. I have had both the run-flats on the Corvette I traded in for my MINI and on my MINI patched. They must be patched correctly by someone who knows what they are doing, for example, never with a plug.

The disadvantages of run-flats are the stiffer ride and the (much) higher cost. The advantages are never being stranded and the weight savings for not having to haul around a spare. Hope this helps. :smile:

 

Run-flats have stiffened side walls that allow you to drive them even with no tire pressure. While the maximum distance is 50 miles, that is for a completely flat tire. The distance you can drive with a run-flat that has some air in it, say 15psi, dramaticaly increases.(Not that I am proud of it, but I have driven over a hundred miles with a run-flat with only 10psi in it and the tire was just fine.) Driving 50 miles on a run-flat tire that has no air in no way comprimises that tire. This technology has been around for over 5 years now.

Run-flats may be patched. Slow leaks are more common than total flats. I have had both the run-flats on the Corvette I traded in for my MINI and on my MINI patched. They must be patched correctly by someone who knows what they are doing, for example, never with a plug.

The disadvantages of run-flats are the stiffer ride and the (much) higher cost. The advantages are never being stranded and the weight savings for not having to haul around a spare. Hope this helps. :smile:

 

well the fix-a-flat/cellphone thing is my plan for around town. On road trips I will re-install the 17s with the run-flats. Seems like a workable solution. I get the around town advantages of regular tires, and don't risk being totally stranded in the boonies by using the run-flats on long trips.

 

Sounds like a reasonable plan, but don't you think that you will occasionally make the unplanned/unexpected road trip and not have time/energy to swap wheels?

 

If you change from run flats to regular does it effect the way the tire pressure monitor works? Will it still function properly?

 

The tire pressure monitor is a purely electronic function that is based on calculating and comparing the relative wheel size. This is a function of each wheel's individual RPM. So, it doesn't matter what kind of tires you have.

If an "unplanned trip" comes up and I don't have time to swap my run-flats back on, then I still have fix-a-flat and the compressor. I'm comfortable with that amount of risk. :smile:

 

Thanks, that's all useful info. I too am curious as to whether anyone is carying the donut spare (and then presumably, a jack too).

 

Just thought I'd throw in my 2cents.

here is a Link to my experiences with local tire companies in Orlando.

:smile:

 

>>Thanks, that's all useful info. I too am curious as to whether anyone is carying the donut spare (and then presumably, a jack too).

Yokohama tires(not runflats). No jack and no spare.
Can of tire inflator always carried. But I like living
dangerously.....

 

I have 20k miles on a plugged run flat with no problems. The rubber strip plug.
I've been using them on all kinds of tires for years. Motorcycles as well. They work well if you install them correctly using rubber cement.

I carry a plug kit, compressor and a jar of rubber cement.
Never use 'fix-a-flat' it will leave a coating of crud in the wheel which will need to be cleaned out with the next tire change.

Oh, I also have a spare. Mini Base with "S" wheels.

 

 

From Firestone Complete Auto Care:

What Is the Repairable Area of an RFT (Run Flat) Tire?
No tire, regardless of its design or quality, is indestructible. RFT tires can be ultimately rendered unusable due to a puncture or other road hazard as well as from improper run-flat or low pressure operation. Some punctures may be repaired under certain circumstances, with restrictions and subject to prescribed procedures.

When driven flat or with low pressure, factors affecting reparability include vehicle speed, load, handling and maneuvering; the amount of inflation pressure lost; and ambient temperature. In any situation, the extent and location of direct damage from a puncturing object or other road hazard are also critical factors.

RFT tires are not repairable in any of the following situations:

If the tire is described as, “Do Not Repair” on the sidewall.
If the tire was operated with inflation pressure less than 15 psi (100 kPa).
Abrasion or other damage is present on the exterior tread, sidewall or bead areas.
Abrasion, wrinkling, or separation is present on the tire interior.
Any condition or damage is present that disqualifies repair of a conventional tire.
Run-Flat Certified Retailers will fully inspect your tire, inside and out, to determine if the tire can be repaired. Tire damage is not always visible from the outside and the tire must be removed from the wheel for a complete inspection.

Note: Some vehicle manufacturers recommend not using repaired tires. Such recommendations apply to RFT tires. Use of RFT tires deemed non-repairable may result in damage to the vehicle, injury, or death. Consult your vehicle owner’s manual or contact the vehicle manufacturer before operating a repaired tire on your vehicle.

- See more at: http://www.firestonecompleteautocare....lmNglzj6.dpuf

 

 

today's winner for sure

and maybe for the year!

Sorry to dis a new user JJ

welcome to the boards and I applaud your reading the old stuff . . .

but b4 you comment, check on the age of the last post ... just a suggestion .... you added to a thread where the last previous comment was 2002 . . . trust me, this topic has been discussed more since 2002! But not in this thread . . .

I made the same booboo ... it is all about the mechanics of how these 'board sites' work .... welcome ... there is a TON of info here ... but some get TESTY when old news appears as new news . . .