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      11-12-2014, 02:57 PM   #1
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Run-Flat, safe by nature, so ride until goes flat? (RF=Upside-down safety rules?)

Take a hypothetical that I hit a pothole hard about two weeks ago with my front 19” Pirellii P-Zero. Car has been driving fine.

Then one day, I notice an inch-gash in the sidewall, about half an inch up from the rim edge, where presumably the rim edge had cut the tire. Through the gash, I can see a tiny bit of the belt inside.

If this was a normal tire, such a cut would be scary. But this is a “special” run-flat tire and the tire is keeping air at a constant 43psi (I tend to inflate close to max pressure for better mileage).

Now if this was a normal tire, I’d swap it out in a flash since my tire could blow out and lose air at any time. But this is a much-ballyhooed “special” run flat. And all you read out there from run-flat proponents is how “extra safe” run flats are, how you can drive 50 miles on a flat run tire while flat, and that a run-flat will not ever blow out “unsafely” on a highway at high speed (as they imply a regular tire will).

Take a hypothetical that I have a 50-mile each way trip into the city coming up at least 65+mph highway speeds to go with the traffic flow.

So I can ‘trust‘ my run flat to not blow out in a unsafe manner at 65mph because of those “super strong” sidewalls the run-flat guys always go on about, and the special run flat tire will get me back home safely since they can drive for 50-miles while flat too. No worries?

Right? That’s the run-flat claim set – why people buy them – now do I really trust it?

Enough to drive such a trip? And keep on driving, until it finally goes flat as its “run flat” name implies?

Am I good to go – because it is a run-flat?

Given that: I want to change out these run-flats when they wear out with Michelins. These are my summer-only set, where I also have dedicated snows I’ll be switching to in late December. Right now at 19K miles, all four summer Pirelli tires look to have one-third their tread height left.

I can see three options.
  1. Replace the one bad tire with a conventional Michelin tire that I’ll be moving all four tires to eventually anyway
    a. Do I have to worry about circumference differences? Traction differences?
    b. In my two calls to local NH tire shops so far, the two best reviewed shops told me they don’t “even have the special machine” needed to remove a run-flat tire from a rim.
    c. So already there’s a problem right there. It’s not easy to take a run flat tire off the rim??
  2. Buy a new Pirelli tire from dealer to last while the other three tires wear down
    a. Wasting two-thirds of the tread life on the new one
  3. Keeping driving the run-flat tire until it finally does go flat, as it and the other tires all wear down together
    a. This tire was designed to run flat – so trust it to get you home when it finally does blow
    b. Watch the gash closely if it gets bigger
    c. Watch for any air pressure drops, aided by the TPMs
    d. Some on web have said their run flats have lasted months with a sidewall bulge and/or cut, they were surprised how long it lasted, where the tread finally wore down as normal.

These run flats allow for different operating rules than the days of normal tires? Run it until it goes flat, and stop fretting about the gash in the sidewall, it’s a safe run flat, so just trust it, since it’s MEANT to be driven until it’s flat?

Would you pro-run-flat guys really trust it just because it is a “run flat” tire?

What’s my best option here – trust option 3 and trust the fact it’s a run flat? Would you trust in the run flat concept and not replace it?
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      11-12-2014, 08:56 PM   #2
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I'd replace that one tire with or maybe both fronts with Michelin Pilot SS in your (I think) 225/40r19 size.

It has rolling diameter of 26.1 which is same as your 255/35r19 rear Pirelli when new.

Your Pirelli P Zero 225/40r19 front has 25.9 diameter new.

You don't have much leeway to put different tires on 19 inch wheels, and you sure don't want to go bigger since you already are having mpg problem.

I have 18's in staGGERED and will go 5% smaller to get more acceleration when I change tires.

The only safety thing I see about run flat is you can get out of bad areas to deal with tire later. I would't run over 50 mph with compromised tire like that, and then 50 mile more when it deflates.
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      11-12-2014, 09:40 PM   #3
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Uhhh. I have never seen a run flat tire have a claim to be driven at speeds of 65mph when damaged or low on pressure.

I've sold my run flats (really easy). If I were you and you're planning on going normal tires, just get them now and sell your 3 good run flats.

Also, the shops telling you that you need a special machine to change a run flat tire are just lying to you. They don't want to deal with it is all, it can be done on a decent tire machine. They're lazy.

I wouldn't trust a bulge in my sidewall, nor a showing belt. That's just asking for trouble, and the front tire is the one you don't want trouble with. It's not an "IF" question, but a "when" the sidewall will give out. Probably going around a corner. Probably at 55.
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      11-13-2014, 06:28 PM   #4
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Quote:
Originally Posted by 0w40X1 View Post
I'd replace that one tire with or maybe both fronts with Michelin Pilot SS in your (I think) 225/40r19 size. It has rolling diameter of 26.1 which is same as your 255/35r19 rear Pirelli when new.Your Pirelli P Zero 225/40r19 front has 25.9 diameter new.
I'm leaning toward this. Just have to find a shop that will do this. I'm getting a sense that no one around here wants to touch a run flat tire.

Perhaps if I tell them it's OK to damage the old tire, that will sway them to try it? Or is it damaging the rim that they're afraid of? The moment I say "BMW" and "run flat" - right away I get "we don't do those... click"

So far all my trips have been close to home (within run-flat range), and the tire is holding up fine even at local highway speeds. No change whatsoever.

So far seems mostly cosmetic. But I wouldn't be doing this with a normal tire. Who knows, this experience might give me a new respect for run flats if it continues to hold up for another 10K miles.
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      11-13-2014, 07:47 PM   #5
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Somebody at some point is going to get that run flat off.

My favorite street tire company is Discount Tire.

I like to buy from Tire Rack, and Discount will match prices and get Michelin PSS, etc.

If you have to, buy the Tire from the Rack, and go to professional shops until you find one.
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      11-13-2014, 09:03 PM   #6
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Tire rack will give you recommendations too, for your area. The place in Calgary that I bought my PSS from got me a better deal than Tire Rack. But TR is really good to deal with.

Believe it or not, my dealer is also very competitive when it comes to pricing for stuff like tire mount and balance, alignments etc.. It might be of benefit to see what they say about price. They shouldn't say much about going to non run flats besides "you won't have the ability to drive" Although, you hopefully have road side assistance.
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      11-14-2014, 06:55 AM   #7
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I forgot about Tire Rack will tell you where a installer is.
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      11-22-2014, 01:01 AM   #8
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just bought a 2015 X1 xDrive i28 M Sport 19" run flat tires.... been driving it around for last two days, my wife's 07 Lexus SC430 has them too but never felt like I was driving a tank like the way the X1 does.... I had a passenger yesterday and asked me what is that like vibrations.... he is talking about the noticeable bumpy ride, he even suggested to check the tites that it feels like I have a flat tire, ha ha

thinking about running another set of tires with 18" rims with 50 series thickness tires
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      11-22-2014, 01:45 PM   #9
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Shoulda bought an Acura. The X1 is supposed to be firm.
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      11-23-2014, 04:27 AM   #10
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I thought my Mazda Rx8 was the deal until I got my X1 s28i M Sport with 8 x18 an 9 x18 wheels.

The X1 is very smooth, and only had some sway at high speed.

I fixed that with 12mm spacers up front to minimize the stagger, and it's the best driving car I've ever seen or driven.

I'm pretty sure I can improve on low speed bumps with non run flat Michelin PSS in a year or so after I get Pirelli P7 run flat off.
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      11-23-2014, 10:57 PM   #11
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I second the vote for Discount tire/American tire. They would laugh at the suggestion of not working on run flat tires. They took my Goodyear run flats off and bought them from me when I bought 18" BMW 322 style wheels and Michelin non run flat tires. Non run flat tires make the X1 feel like a totally different car!
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