New To Having A 4WD? Here's Why Your Spare Tire Should Be Normal-Sized

The purchase of your first part-time 4WD vehicle can set you off on the road to fun and enjoyable experiences. Not only will you be able to have better control of your vehicle in inclement weather, but you will be able to go off-roading and pull heavy loads up hills without any problems. While there are many differences in 4WD vehicles as compared to other types of vehicles, there is one important difference that you need to understand—the spare tire needs to be the same size as the normal tires. 

On regular vehicles, a spare tire is often smaller than the other tires. Spare tires should be normal-sized tires on 4WD vehicles in order to protect certain components of the drivetrain from damages. Here's what you need to know about the drivetrain system and what can happen if the spare tire is too small. 

Drivetrain Components & How They All Work Together

The drivetrain components of part-time 4WD vehicles are the transmission, the front and rear differentials, thefront and rear drive shafts, the front and rear axles, and the transfer case. Don't confuse the drivetrain with the powertrain. The powertrain is the engine, the transmission, and the drivetrain. 

The engine creates power. The transmission takes that power and transmits it to the rest of the drivetrain at various speeds in order to make your wheels spin, which makes your vehicle go. To get all four wheels to move at the same time, you engage the 4WD, which uses the transfer case to transfer power equally to both differentials. The differentials then tell the wheels to rotate at either the same speeds when going straight or at different speeds when turning.

The issue here when one tire is a smaller size is that the differential gets "confused" when the side with the smaller tire doesn't rotate at the same speeds as the tire on the opposite side of the same axle. This confusion causes mechanical stress on the teeth of the gears inside the differential. In turn, this causes mechanical stress inside the transfer case. 

What Mechanical Stress on Differentials & Transfer Case Can Do

Mechanical stress inside the differentials and transfer case can create a noise that you may not notice until significant damage has already been done. The noise comes from the teeth of the gears inside the components grinding together and wearing more intensely than they would if the tires on the vehicle were all the same size. At some point, if the vehicle is driven with a smaller tire continuously, the gears can bust apart and blow out of the differential or transfer case. 

The mechanical stress can also cause the fluid inside the components of the drivetrain to ruin the transmission if the entire drivetrain system uses the same fluid. As the gears wear down, they produce metal shavings and small particles of metal that can get into your transmission and the rest of the drivetrain components. Should this happen, your vehicle may become sluggish, as your transmission is unable to switch gears.

All of this can be avoided by making sure your spare tire is the same size as the other normal tires on your 4WD vehicle. It's important to get into the habit of checking the air pressure of the spare tire. Also, be sure when it's time to replace your tires that you replace all of the tires at the same time with tires that are the same size. If you have driven your 4WD with a smaller tire, check the transmission fluid for slivers of metal and a burned odor. 

To learn more, contact a company like Huntington Beach Transmissions.

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About Me

Learning More About At-Home Auto Service I have never been an especially handy person, but a few years ago I decided that I needed to learn more about my vehicle. I was tired of always relying on someone else to fix things, so I began reading more and more about the process. I realized that there were a lot of things that I needed to do, so I began taking a little course on at-home auto service. I still have a lot to learn, but now I can at least go through and change my air filter and check my oil. Read this blog to learn more about auto service.




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