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Significant tire weight difference will affect ride quality

Published April 25, 2013

Q. I’m considering new tires for my two-wheel drive Toyota Tundra pickup now that the winter tires and wheels are coming off. The factory size is P275/65R18. I always go for Michelin and am looking at the LTX MS2. This popular light truck tire looks perfect.

I see that this tire/size is available in passenger (P) and light truck (LT) designations. I like the idea of LT for puncture resistance and increased load capacity. Can you tell me if the comfort level and fuel consumption will suffer noticeably if I go with the LT rather than the P version? The LT must be a much heavier tire? I’ll pay for good quality, but I’d sure like to avoid a mistake when it comes this kind of money.

A. You are correct about a weight difference between LT and P rated truck tires. In this case, the Michelin LTX MS2 weighs 42 pounds in P designation and 50 pounds in the LT version. So an extra eight pounds of unsprung weight per corner of the truck is significant. That is almost 20 per cent more weight. Fuel economy drops, ride quality falls off and the will lose some agility.

LT tires should be used if you are planning on heavy loads. The P version of the tire maxes out at carrying 2,601 pounds at 44 psi. The LT tire can handle up to 3,415 pounds at 80 psi. So the difference again is huge. Note too, the pressures the LT tire can handle are 80 psi. That kind of number equates to a rock hard ride. They can be run with less air but then the load capacity goes down.

Fundamentally you need to analyze how you drive, what you carry and just how important comfort is to you. If you haul heavy stuff on a regular basis, go LT. If you drive around lightly loaded and never need to exceed 2,601 pounds per tire then I’d go with the P version. The ride comfort of the P tire will be noticeable. It is built to absorb bumps, plus it runs at much lower tire pressures. The LT version of the tire is built tough to haul 814 pounds more than the P. Yes it is more puncture-resistant but at quite a heavy price in comfort.

Q. I have just wrapped up my winter tires in plastic bags. Will they be safe from ozone from the forced air gas furnace that is 10 feet away?

A. Ozone is generated by the operation of electric motors, such as your furnace, so plastic bagging them has no real defensive effect. There is not much ozone produced by a furnace motor, but the further away from the furnace you can store your tires, the better. The ozone effect lessens the further you are from the source.

Q. I have stored my 1996 Jaguar XJS convertible during the winter for many years. Lately the ride has been somewhat heavy, feeling any little thing on the road with significant tire noise. I don’t drive this car at 160 km/h. I enjoy driving through the countryside and taking side roads instead of the motorways, as passing a convoy of trucks is not the greatest feeling. But of course I don’t avoid the 400-series highways. Which tire or tires do you suggest to use on this car that is good on gas, low on noise and comfortable to drive? The tire size as per Jaguar is 225/60-16.

A. That is a fine old Jaguar you have. Since you are interested in safe, comfortable motoring, I suggest you go with a “Grand Touring” class of tire rather than a “Ultra High Performance” category tire. These tires will all still have the correct load and speed rating for your Jag but will have better ride comfort than a tire that is engineered for ultimate grip.

Sixty series tires are not much in vogue these days, even for family sedans, so where you would have had a choice of dozens of models years ago, we are at just a few choices today.

The top ranked tire that fits the bill is the Michelin MXV4. It is the newest technology from Michelin and will give quiet smooth riding. Its only downside is price. Michelin does charge for the tech. At just over half the price of the Michelin, you can consider the General Altimax HP. It does most things quite well. General is a Continental Tire owned company and their products are just less expensive than the regular Conti line.

In the middle price point between these two tires is the Bridgestone Potenza RE97AS. It is smooth and comfortable and is Bridgestone’s newest version of tire for luxury sport coupes and sedans. In wear, the Michelin will last the longest, the General the shortest and the Bridgestone in the middle.

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

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