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Tire Guide

Tire plug no substitute for a patch

Published July 3, 2013

Q. I recently experienced a vibration in my car within 10 km. of home that felt exactly like a seized brake calliper. I noted it and drove gingerly home. When I got there, I saw my near flat and the tire was very hot; there was one screw in the middle of the tread face. Should I replace the tire after such an extreme heat cycle?

My question to you regarding extreme heat build-up after a near-flat was answered when the tire was pulled for a plug and patch. The carcass of the tire had a lot of rubber crumbs in it and frankly, just didn’t smell right either. The shop where I took the tire said that they would not try to fix it no matter what. As such, they have earned my confidence. Just because a tire “looks” okay after a near “death” doesn’t mean it actually is.

I’ll never understand why people don’t realize that their tires are the most important safety feature on their car.

A. I couldn’t have said it better myself, tires are hugely important. Sounds like you had quite an adventure with that tire. I always recommend complete dismounting when a tire has had a flat. The first reason for this is obviously to check for damage; the second is that the only correct repair is a patch-plug combo from the inside of the tire, assuming the tire can be repaired.

Drivers are often put off by the cost of a proper tire dismounting, repair and rebalance, so they opt for the easy fix and shove in a plug from the outside. Sometimes this kind of repair works, but it can come apart later. If the tire’s steel belts are cut and damaged, the push-in plug does little for the long-term life of the tire. Exposed ends of the steel belts can start to rust and the rust works its way along the belt weakening the tire structure.

Plugs pushed in from the outside are constantly fighting centrifugal force as the tire rotates. A proper repair is a plug-patch put in the tire from the inside. The patch seals the air chamber and the block becomes part of the tire tread. A tire that has bits of rubber crumble or smells smoky should never be repaired.

Q. What brand of rubber should I but on my Porsche Cayenne S? I want to upgrade to 20-inch wheels from the 19-inch ones it came with. A tire shop is suggesting a Goodyear Eagle P275/45R20, 110V, XL, LS2, NO, TL. I want the vehicle to keep its sporty feel.

A. There are three tires to consider: the Michelin Pilot Sport PS2, the Goodyear Eagle F1 Asymmetric SUV-4X4, and the Yokohama Parada Spec-X. These three are all “Sport Truck” tires.

I suspect that is not the Goodyear they are quoting you on. As it has the “NO” rating, which is Porsche-approved, I suspect it is the Eagle LS-2. The LS-2 is approved by Porsche. The others mentioned above are not. The LS-2 is a “Grand Touring” tire. All the ones on my list are truck sport tires.

It depends on how you drive on the street if you will be happy with the grip provided by grand touring tires. The three tires I mention will all out-grip the LS-2, if that is ultimately important.

The Michelin outgrips the other two by a bit in wet and dry. The Yoko and Goodyear are about equal. The Michelin, of course, is the most expensive, the Yoko the least expensive. In consumer satisfaction surveys, the Yoko comes out number 1 in the sport-truck category.

Send tire questions to: thetireguy_1@hotmail.com. Mail volume prevents personal replies.

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