Question in subject line... reason for asking is this. My car did not come from the factory with a spare tire nor any tools to change it. The factory tires are run-flats, but they're expensive, wear out quickly, and there are better options out there. Also, if you get a flat in the middle of nowhere, and can't get the tire repaired within 50 miles, you're screwed - and your expensive tire is unrepairable. Also, my winter tires are NOT run-flats. Factory option - space saver spare in tire bag, with a little foam insert that holds the jack and lug wrench. OK, but you still have the 50 mile limitation as well as a similar speed limitation to a flat RFT - so now you have stuff, but it's no more useful than nothing at all. My idea - for the summer, I will put one of my winter wheels and tires in the tire bag, along with the tools, and use the extra space under the foam insert to hold other emergency stuff like jumper cables etc. that would otherwise be taking up space in the trunk anyway. Before winter, I will attempt to acquire another wheel that matches my winter set (because 17s are cheaper and lighter than 19s) and an acceptable used tire. My theory is, this way, no matter where I get a flat if it is inconvenient to me to stop and get the tire repaired quickly, I can travel on as far as I like before having to deal with it. I just realized something however - my winter tires are directional, so whichever one I put in the trunk, there's a 50% chance that if I do get a flat and need to use the spare, the tire will be mounted the wrong way on the wheel. I understand that traction will be compromised somewhat, but how dramatic is it really? Should I make a point to get a non-directional spare tire as quickly as possible or is this no worse than using the donut, say? I haven't had any experience with wrong-way mounted tires, because I always paid attention to the little arrows on the sidewalls :) My gut feeling is that it's still preferable...

Any loss of traction by being on "backwards" can easily be compensated for by driving 10 mph slower then you otherwise would. Some years back one of the car mags did a story about the use of the skinny doughnut spare tires that had started coming with Corvettes as spare tires. They mounted the spare and then ran the car thru the same sort of performance tests they would normally do. Turned out it didn't make all that much difference nor did it make things unsafe. If I were you I'd just get the temporary tire that would have come from the manufacturer and forget about al the other folderol. Odds are you'll never use it and even if you do I'm sure it will much farther then the 50 miles it shows on the sidewalls. The only reason not to would be if you had a limited slip diff and had to use the same rolling diameter and the temp wasn't the same. You'd have the same problem using your winter tires, .. if you have limited slip you want the same diameter .. OR.. you would need to drive...

How bad is it, in the grand scheme of things, to install a directional tire the wrong way?

May 10, 2013 48 Replies

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AD 13 years ago

rather, I feel that a tall profile couples to fewer layers if plies increases those odds and, thusly, one has to reduce speed (unnecessarily) even if the suspension and the rest of the car can take the beating (or it's a beater car and you don't care if it can, which was my case when non dohnut 175 13 70 tire got sidewall damage from a pothole or a series of such on moonscape rally grade freeway far, far east close by the tahoe twin lake

so it had to be welded and an inner tube went in for safety

the government had fixed that rally grade road since then. it's kinda sad cause it would've been a great sidewall stress testing grounds for the tire manufacturers

(for those that care to sell anything in this market anyway)

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AD 13 years ago

I'd let the two of you to fornicate in this branch of the trollingdiscussion but I'm equally clueless here either. Why are sidewalls bias ply?

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AD 13 years ago

weird that goodyear even bothered to specify the number of plies, if I had to guess that was the tread unless that was a tire marketed for an off road use

the definition of normal is dependent on the locale

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gpsman 13 years ago

Of course you have... that's how you determined donut spares are "no more useful than nothing at all"... -----

- gpsman

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Nate Nagel 13 years ago

Actually that was on a vehicle equipped with a full sized spare identical to the tires delivered with the vehicle, for which I was very appreciative.

nate

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jim beam 13 years ago

logic fail!!! amazing logic fail!!!

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jim beam 13 years ago

not all plies, but you need bias to transmit torque. look at wire spoke motorcycle wheels - they use tangential spoking for the same reason. [undriven, unbraked works as pure radial, but most are braked, driven, or both.]

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jim beam 13 years ago

i must add to this. contrary to what i said earlier, and in agreement with what nate observed about only one ply, i have done some fact checking and it does indeed appear that some of the cheapest tires are only one radial ply. this is somewhat surprising not only given the above, but in terms of reliability too. i intend to look into this further, but conventional wisdom is that you need a tangential component and therefore multiple plies for the reasons stated.

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Nate Nagel 13 years ago

I have in front of me a Continental donut T135/80R17

Sidewall: 1 ply Rayon Tread: 2 plies Steel 1 ply Rayon

For an example of the type of wheel clamps that I was referring to earlier as being damaging to alloy/chrome wheel barrels, I was over at my friend's shop yesterday and his tire changer is a John Bean T900, it has exactly the kind of clamps I hate. He doesn't have the soft pads for it as they were an optional extra when he bought it - much like most shops who do not cater to enthusiasts or detail freaks. AFAIK the tire machines that Snap-On sells are relabeled John Bean models.

nate

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