I had a flat tire a while ago, so I mounted the space-saver spare. I'll admit I left it on for way longer than the owner's manual suggests. Eventually, I replaced it with a full-size tire, but I've always wondered why manufacturers say you shouldn't use the spare for longer than necessary.Since the spare tire is used so infrequently, carmakers have switched to narrow, compact spares to save space and weight. Of course, a spare tire is a lifesaver when regular tires go pop, but leaving the temporary tire on for longer than the manufacturer recommends invites a host of problems. First, a temporary spare isn't as durable as a normal tire. The real strength of a tire comes from the plieslayers of steel and polyester underneath the rubberand spares don't have as many plies as regular tires. A typical space-saver spare has only one layer of polyester in the sidewall and two belts of steel with a layer of polyester in the treadabout half as many plies as a normal tire. This greatly limits puncture resistance and cornering ability.

In addition, as the name implies, space-saver tires are intended to take up less room in car and crossover trunks so that those trunks can be deeper. For that reason, these tires are narrower and have a smaller contact patch. This reduces the amount of traction for the tire, increasing stopping distances and making handling potentially unpredictable in emergency maneuvers. It also means ABS and traction control aren't as effective at keeping you out of danger. And you're not going to have the same ground clearance. If you're towing a trailer, you'll have to leave it behindspares have much lower load ratings than regular tires. Long-term use of the spare can cause a serious mechanical issue, too: The smaller-diameter tire can put a lot of stress on your differential. The differential has a tricky job. It transmits engine power to the wheels from the transmission, but it also lets the left and right wheels turn at different speeds. This is essential for cornering. In a turn, the path of the inside wheel is shorter than that of the outside wheel, which means they travel at different speeds.

When your car is driving in a straight line, the differential isn't in use and there's little wear and tear on its gears and bearings. But because the spare is smaller than the opposing wheel on the same axle, it must turn faster to keep up with the speed of the car, making the differential work to account for the variation. It's as if the car is constantly in a turn. Leave the spare on long enough and the grease lubricating the differential will begin to break down, accelerating wear between the gears and the clutch plates if it's a limited-slip differential. For all these reasons, manufacturers suggest keeping speeds below 50 mph and using the spare tire only for limited distances if possible. If a compact spare is ever damaged, either the tire itself or the wheel, the entire spare should be replaced rather than repaired. And don't forget to check the pressure in your spare every time you check the pressure in your other tiresit's important to make sure your safety net is, in fact, safe.

Got a car problem?Ask Ben about it. While we cannot answer questions individually, problems of general interest will be discussed in the column. Clint Eastwood Drives an Awesome GMC Typhoon Pickup Truck Why Your Insurance Company Can Deny Your Claim and Get Away With It 12 Embarrassing Cars Built by Excellent Automakers This Brand-New $130,000 Plug-In Hybrid Isn't New at All Peek Inside a Running Motorcycle with This Transparent Engine Cover Meet the World's Fastest Monowheel Rider, And Watch Him Crash a Little BitCost Of A New Cat D9 Mercedes-Benz Concept Van Is a Drone Delivery VehicleCar Seat Warmer Cooler Dodge May Make an All-Wheel-Drive Challenger Hellcat Next YearHow To Hang A 20 Lb Mirror This Beefed-Up DeLorean Is the Time Machine You Need

"The Onion" Made a Real Commercial for This 3-Wheeled Car 764 posts, read 1,499,454 times 6,268 posts, read 8,075,575 times 4,269 posts, read 2,424,805 times 2,473 posts, read 3,671,627 times 5,552 posts, read 7,381,236 times Originally Posted by NARFALICIOUS Because the question they asked was "Is it a coincidence?" 2,341 posts, read 5,611,172 times 8,835 posts, read 9,912,143 times Originally Posted by daboywonder2002 The first question that I would ask is... When was the last time that you checked the pressure in your spare tire? If the answer is...Isn't my mechanic supposed to do that for me?...or...I checked it more than 1 year ago, then you have found the culprit, and the culprit is...you. Unfortunately many people give little attention to the 4 tires that provide the only contact between their car and the road, and even more people give little or no attention to their spare tire. Every tire will lose some pressure over time, and if that time period has been...extensive...then it is entirely possible for your spare tire to have gone flat in the...who knows how long...interval that elapsed after the last time that its pressure was checked.

The moral of the story is that the most basic parts relating to automotive safety are your tires and your brakes. And, "tires" includes your spare tire. If you ignore them, or if you expect a bald tire to be a reliable item, then you really have to re-think your approach to automotive maintenance.Apr 16th 2010 at 12:00AM I own a 2004 Chevy Aveo. The other day I got a flat and I had the spare installed. It’s a fake (one of those “donut” spares). I haven’t had a chance to buy a new tire yet, and I want to know how long can I drive before I replace it with a real . Funds are tight right now. Sarah from Burlington, VTSarah, Wow, Sarah asks the kind of question that seems to crop up more and more these days. I guess the slow economy has everyone strapped for extra cash to meet unexpected events. Let’s take a look at Sarah’s concern in detail.How Long Can I Drive With A “Donut” Spare?Donut spare tires are not made for extended service. They have no tread to speak of;

the carcass or body of the tire is not reinforced and there is no tread belt to protect it from projectiles and road imperfections. The tire is designed simply to get you to a repair facility. Most of these tires offer a maximum life of 70 miles.You may notice poor cornering, handling, and braking characteristics. The donut spare has a smaller footprint than a conventional tire, which translates into diminished braking and handling. With the donut spare in place, you may find that, when braking, the vehicle dips to the side where the donut was mounted. Also, you may notice the vehicle pulling to that side.The use of donut spares is a cost and space cutting measure. Typically the donut spare takes up much less space and is cheaper to manufacture than full size tires and wheels, which translates into more profit for the car makers. It’s quite a compromise and a loss for the consumer.Can I Put A Full Size Spare On My Car?Yes, but the question is: where do you carry and stow it? Years ago, cars had spare tire wells to fit the full size spare so that it was out of the way.