Quote:
Originally Posted by JamesNoBrakes
Please explain how using sealant on a run-flat could lead to worse situations than with a regular tire? I'm still not understanding what you are saying. Both would seal the hole if it's in the right position and not too large. Only, in the case of the run-flat, if this is successful, you get to save the run-flat and get away with just a plug for long term, rather than ruining the run-flat by driving on it. In the last 20 years, ever low/flat tire I've had was noticed when I returned to the car and either saw a low tire, or was alerted soon thereafter by TPMS. If you've got 20psi, you can probably make it to a shop in the city just fine with nothing. If it's out in the middle of nowhere, then you need to plug that hole.
The reason cars with run-flats aren't going to come with sealant is because the manufacturer takes a minimalist approach. I mean hell, they could give you a spare, real jack, run flats AND sealant. But they aren't going to do that, they are going to do the minimum that works and they don't care about "saving" the run-flats. They want to sell you more.
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The biggest risk comes from sealing a run-flat that's been used at low enough pressure for long enough to damage the sidewall. Putting sealant in a tire like that fixes the hole but leaves the tire with diminished structural integrity. Result is that the next failure will likely be more than just low pressure and can turn into a bad situation very quickly.
Again, I'm not saying you can't *ever* use a sealant kit on a run-flat, but it requires more diligence to use appropriately. In the scenarios you provided, yes if you come out to your car in a parking lot and see pressure is low you can inflate/seal it to get it to a shop for repair. However, if the leak is that slow you probably aren't needing sealant to get it somewhere for repair. You're lucky that you've only ever come back to flat tires while stationary. I've seen plenty in my 20 years of driving as well, and not all have been like that. Most applicable to this topic, I've picked up a curled strip of metal on track and I've had a friend pick up some debris on the street. Both resulted in rapid losses of pressure before even getting stopped but weren't bad enough that they couldn't be sealed.
Lots of different variables (initial tire quality, driving speed, time/distance driven at low/no pressure, tire age/condition, etc.) influence if a run-flat can continue to be used safely or needs replaced. Any mechanic that knows their stuff won't repair one that's been driven on while low, not just because they're trying to sell more tires but because it opens them up to liability of the tire failing sooner and more catastrophically. In the case of my friend with the road debris I mentioned, that was a run-flat tire and the little driving they used to get the car stopped from 75, loaded in a trailer, and unloaded into the garage there was a light coating of powder inside and no shop they took it to would touch it.
Unfortunately, not everyone knows this and there are absolutely people out there that would drive for a while on low/no pressure and eventually "fix" it by pumping some sealant in and calling it a day. Seeing that it holds pressure makes them think everything is fine even though they're actually a hazard with a tire that's much more susceptible to blowing out. Sure there's some cost and weight savings for OEMs using run-flats and not including an inflator, but those aren't the only reasons behind the choice. It also protects from a customer suing the OEM because they saw a provided sealant kit and thought that was all that was needed to repair the tire.
I realize saying, "sealant isn't supposed to be used with run-flats," isn't a complete truth. There are some cases where it can be useful and save the tire from needing replacing, but knowing that the majority of people aren't paying close enough attention nor know the nuances of when a run-flat can be repaired vs. replaced it's the safer broad statement to make without going into a more in-depth discussion.
Quote:
Originally Posted by Paulman
I see the kit referenced in the owners manual but maybe it’s just for the SS?
GM should have clarified that the V6 1LE isn’t equipped especially since the space is there in the trunk
I understand the desire to save some weight with no spare but like said above, if you’re out in the middle of nowhere it could be rough
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The kit will only be included with cars that don't have run-flats. This includes the SS 1LE, ZL1, ZL1 1LE, and maybe some of the lowest trim cars (I don't recall what tire options there are on the lower trims). All trims share the same owner's manual so it'll be referenced there. They also all share the same foam trunk organizer so there will be an empty space where it would go on the trims that come with it. Dealers should all be aware of this as well and be able to confirm that vehicles with run-flats don't come with sealant.
As is the case with nearly every decision, it's a set of trade-offs. If anything, run-flats are
better at handling issues in the middle of nowhere. They can handle any puncture that sealant can fix, but they can also still be driven with some of the larger gashes that a sealant/patch/plug kit could never seal and you'd be stuck sitting otherwise. They also can just be driven away instead of needing immediate repair (because you know there's someone out there driving that either doesn't know how or doesn't want to be bothered with stopping to fix a tire, even if it's as simple as filling with sealant). The trade-off is it costs a lot more to replace the tire(s) and there's a much greater restriction on being able to repair it.