Run Flat Tires?

run flats are a very important consideration when running the next police baracade or during the get away from your next bank robbery......... those spike sticks can really ruin your day during a get away when your mind is on all the cash in that bag in the back seat..... and how to dump your idiot associate sitting next to you in the car............. :lol: :lol:

 

I suspect they might have very high rolling resistance. You would lose more energy to rolling resistance than to mass.

 

<div class='quotetop'>QUOTE(Rangerdavid @ Feb 26 2007, 09:49 PM) [snapback]397015[/snapback]</div>

Please. If you've ever had to change a tire on I-40 in RTP at 6:15 one evening with cars whizzing by your head at 85 MPH, then run flats start to make a lot more sense.

I have to think that extra 8 lbs is going to take some gas, and they probably do have higher rolling resistance, although just thinking about run flats its seems like they would be a fairly stiff tire, so perhaps not.

 

Any tire would be a run flat before I would change a tire by traffic like that. It is better to trash a tire than take a chance, so just keep driving until you can get well off the road. Think about the dash cam clips from COPS where the police have to leap out of the way as a car careens out of control.

 

<div class='quotetop'>QUOTE(NoMoShocks @ Feb 26 2007, 11:37 PM) [snapback]397066[/snapback]</div>

The tire was trashed, it doesn't take long at highway speeds, and I needed to get past the construction barrels to an open shoulder.

 

<div class='quotetop'>QUOTE(DKSH @ Feb 26 2007, 09:43 PM) [snapback]397010[/snapback]</div>

205s being a wider tire will probably decrease your mileage more than the weight.

 

<div class='quotetop'>QUOTE(DKSH @ Feb 26 2007, 09:43 PM) [snapback]397010[/snapback]</div>

I was getting some Nokian snow tires on my Audi a few years ago at a very large tire place up in Lancaster PA. I was looking at run flats and run flat adaptors while I was waiting. The manager there was very negative on them because of ride issues - increased noise and poorer handling. He talked about a little old lady who insisted on putting them on her new Cadillac and said the ride quality was terrible - harsh on bumps and a lot of increased noise. They sold them, they didn't recommend them unless you had special circumstances.

I expect that there may be some improvements in the 5 years or so since I was told this, but that 8 lbs of unsprung weight has to affect handling. Also, if the tires flex enough to have the run flat part press on the road, the harsh ride effects come into play. This may be less of a factor with the higher pressures we tend to use in our Prius's unless you run at the manufacturer's recommendation of mid thirty's.

- Tom

 

I looked into run flats 2 years ago and got alot of negatives from the tire places.
they need special tools to install them that alot of shops don't have.
They don't stock any tires so it would be a special order.
The tires are very expensive .

besides all that, the prius tire pressure monitor system SHOULD give you enough warning of a pending flat that you can make it to a gas station or tire repair place.

 

Our Honda Odyssey has the Michelin PAX run flats. We got a flat once, well my wife did, and it was a reassuring feeling that I knew she could make it home without stopping. The PAX tires can go up to 50mph and 100 miles while flat. I'm big beliver of the technology. We have the Touring Edition Ody and I can't really say if the ride is any worse than a non PAX Ody, but I wouldn't say it is harsh or noisy.

 

Ask the guy who pulled up to the Kal Tire place I was at getting my Nokians rotated. He was driving a BMW 7XX. Very nice car, with runflat tires. He had a "flat" in one of them. The techs pointed out the warning on the sidewall "Do Not Repair Under ANY Circumstances!". So he had to buy a new tire, at around $700 Canadian. He was not happy, until he was informed if he had trashed the wheel -IT- would have cost $2500!

How often do -good quality- tires go flat? Not the "rim protectors" the Prius comes with, good quality tires. My take is it's better to use a good quality tire than run flat tires. I'm averaging one flat per ten years, and I take gravel roads a lot at speed as well as "normal" driving. For emergencies, where you just cannot take the time or chance to change a wheel, carry a can of instant "flat fix". It will ruin the tire, but that may have already happened anyway. Not a solution for every instance, but it will work most of the time.

The extra weight of the run flat tire will make the car ride rough, combined with the extra stiff side wall, very rough. If you want to switch to run-flat tires, the "proper" way to do it is to re-tune the suspension with better (stiffer) shocks to handle the extra weight of the tire. The car would still ride rougher, but not as bad as the stock setup with run-flats.

And, of course, now that we've talked about flat tires, I'm bound to get one today!

 

<div class='quotetop'>QUOTE(DKSH @ Feb 28 2007, 07:18 PM) [snapback]398144[/snapback]</div>

At $212 a pop + shipping + local mounting and install you are looking at over $1,000 in rubber! With only a treadware rating of 240 don't expect them to last long. Also get a flat and you will be replacing all 4.... I do not know but $1,000 buys a lot of AAA in my book unless you live in the middle of no where.....

 

How can you trash the wheels with run flats? The whole reason for run flats is that you can safely keep driving even with a flat, with no damage to your wheel. Take turns, go on the freeway, just keep driving. There sure seems to be a lot of misinformation about run flats as there is about the Prius.

 

<div class='quotetop'>QUOTE(Texas911 @ Mar 1 2007, 07:28 AM) [snapback]398400[/snapback]</div>

There isn't any mis-information I've seen in this thread about trashing a wheel. I mentioned it in my answer as that was what I was told. In other words, the BMW owner drove a few hundred Km on the flat. If it -hadn't- been a run flat he would have trashed his $2500 wheel. So he should be happy with the $700 run-flat tire.

It is possible to trash a wheel mounting a run-flat tire, as they are much stiffer. This, however, would be because the tire tech was careless or ignorant, not because the tire -will- trash a wheel. Same applies to very low profile tires.

BTW, read the info on the runflat tires. Max speed when flat is usually speced at 50 MPH/80 Km/hr. This is NOT a freeway speed, unless you want to be run over! Even "runflats" will overheat and disintegrate if abused.

 

<div class='quotetop'>QUOTE(David Beale @ Mar 1 2007, 10:08 AM) [snapback]398484[/snapback]</div>

I beg to differ, there are freeways in Houston that are limited to 55mph. 50mph is clearly freeway speed. I wouldn't be haning out in the left lane, but it would be doable. Enough at least to get you off the freeway and into a better spot to replace your tire or at least make it home. That's the beauty of run flats. I'd rather my wife drive home and let me take care of the flat.

 

<div class='quotetop'>QUOTE(DKSH @ Feb 26 2007, 06:43 PM) [snapback]397010[/snapback]</div>

I'm surprised that no one has already made that comment that I will make: if you switch to run-flat tires and the increase of a few pounds, how much weight do you save by deleting your spare time and any related tools? In general I think that cars w/ run-flat tires don't come with spares. That aside, I have heard nasty things about cost and wheel damage associated with changing run-flat tires. That and the fact that I haven't gotten a flat tire in 15 years make me disinclned to change anything...

 

<div class='quotetop'>QUOTE(scoot @ Mar 1 2007, 10:49 AM) [snapback]398518[/snapback]</div>

It's a much more complicated formula than that. Because, as someone has already mentioned, the added tire weight is unsprung (i.e. it does not benefit from the shocks and springs that the rest of the weight in the car does). Increasing the weight of a tire affects driving significantly more than adding a similar weight to the cabin (for instance).

 

My brother has run flats on his Beamer which he got new. Just passed 17,000 miles and the run flats are shot and must be replaced. That can get quite expensive over the life of a car, they are not cheap to begin with.

 

My Mini Cooper has run flats. They are good for 50 miles going 50 miles an hour. I also have a "donut" spare. The Cooper S does not have a spare because there is no room for one in that model.
I've had two Mini Coopers and both needed the tires changed around 25-30k miles. At over $800 they are expensive. Not all tire stores carry them in stock and if you are on a trip out of your normal dealer's area this can be an issue.
I'm trading in my Cooper (29 mpg avg.) this weekend for a Prius. I've been reading all I can here.

This is quoted from a Mobil 1 site article on runflats: