From time to time, your ATV does not behave the way you want it to. Nothing great lasts forever, right? One of the most common issues you may experience is that your bike suddenly or gradually starts pulling or drifting to the left or right. If you are lucky, there may be an easy explanation for your problem. Let’s take a look at some of the most common reasons an ATV pulls to either side and, of course, how to fix them.

The most common reason why an ATV pulls either to the left or right is a difference in the front wheels’ circumference due to different air pressure. Wear or damage to the various components in the undercarriage of the quad can also result in these kinds of issues and may require replacement. If this doesn’t resolve your problems, the front wheel alignment may be out of order and needs to be addressed.

How do you identify the issue that is causing problems on your ATV?

As you’ve probably understood by now, there is not just one single reason why this happens. To find the actual reason why your ATV is wandering off into the ditch when you want to go straight, you need to do some troubleshooting.

Although I have no solid statistics to prove what underlying cause happens most frequently, I recommend you follow the checkpoints below by order. I start with the easiest to check issues and should be examined before you start spending time and money on more uncommon and potentially more complex solutions.

Checkpoint one: A difference in wheel circumference

In my experience, the most common reason, and definitely the most straightforward issue to check and fix, is the different circumference of the front wheels on either side.

Basically, this means that for each time the wheels turn, one wheel drives a slightly longer or shorter distance than the other. This will most certainly make your bike pull to the side, which has the smallest circumference wheel.

But both the wheels are identical, you might ask, and they have been in use for the same amount of time and mileage. How can this even be an issue?

The most likely cause: Different tire pressure in the front tires

ATV tires are relatively soft and flexible, so they basically act like balloons when you put air into them. Although not as visible as on the birthday type, they still expand quite a bit when inflated with more air.

More air equals a bigger tire with a larger circumference. If the ATV pulls to the right, the front right tire pressure might be too low. If it pulls to the left, the same applies to the left tire.

What you need to do, is to make sure both tires are set with the correct factory specific tire pressure or to your personal preference for the intended use. Use a good tire pressure gauge to check your levels.

Most ATV brands come with one in the tool-kit. If you can’t find it I strongly recommend getting one as soon as you can, they are not expensive. Just a two to three pounds difference between the tires can be enough to create an issue.

You should check both front and rear tires. Although uneven pressure in the rear tires is less likely to cause your pulling issue, it’s worth controlling them when you are at it. It’s not good if they don’t have the same circumstance, as that will cause them to “fight” each other and may cause premature rear diff wear.

I keep this cheap digital one in my tool kit at all times, and the accuracy is good enough for my use.

Caution! Never exceed the maximum tire pressure, usually written on the side of the tire.

If you are not sure what pressure is safe or optimal for your machine, please refer to your user manual.

Note that there might be different pressure ratings for the front and the rear tires. What is important in this case is that both front tires have identical pressure, and also, both rear tires read the same levels.

Now you can find a tape measure or a piece of string to measure the circumference—Jack up the quad for proper access. If you use the string, you just put a mark when you measure one side, and then the other side should be identical. If they are the same, you are good to go!

Here is another easy method you can try to check if the circumference the same: Place your ATV on a level, smooth ground, and with a piece of chalk, make a mark on the sidewall of each front tire at the very bottom.

The wheels should be pointing straight forward, and the ATV should be in neutral. Then push the bike forward until the tire has made two or three full turns, and the mark you just made on the tire is back at the bottom where it started. Pay attention to only one of the tires when doing this. Then have a look at the mark on the opposite tire. Ideally, this should also still be at the very bottom. If this is not the case, the circumference is not the same as on the other tire.

If the ATV is pulling to the right, the right tire likely has the smaller circumference, and if the ATV is pulling to the left, the left tire is likely the smaller one.

What if the tire circumference is not the same using correct tire pressure?

It’s important to know that even if both tires are at the same pressure, the circumference is not necessarily the same.

While this is generally more true for bias-ply tires than radials, the tire dimension will sometimes be altered over time, simply because of treating them differently. If you at some time have put more tire pressure in one of the tires than you usually use, this may have stretched the tire and altered the circumference by as much as a couple of inches. This may happen even without exceeding the maximum tire pressure.

You can try to correct this to put about 90% of the maximum tire pressure in both tires and leave them for a couple of days. I don’t see the need to go all the way up to maximum pressure, as 10% below maximum is still far over normal riding pressure and should have the same effect.

Doing this procedure may stretch the tires evenly. Then you should adjust the pressure back down to your preferred riding pressure and recheck the circumference.

If this does not make the tires the same size with identical tire pressure, you can inflate the smallest tire slightly more than the other until the circumference is the same. Then, the next time you buy new tires, you remember to never put more air in one of them than the other!

But remember, and this can not be said too many times: Never exceed the maximum rated tire pressure as an exploding tire may be fatal, even with lower pressure levels like ATV tires usually should have.

Checkpoint two: Check for wear in the rod ends, ball joints, bushings, and bearings

For this step, you need to start by jacking up your quad so that all four wheels are off the ground simultaneously. There are many ways you can do this; just make sure the bike is stable.

I recommend that you find a hard level surface like a concrete floor and use a good quality jack. I like placing a couple of wooden blocks under a flat spot in the center of the quad, one in front and one in back.

If you like maintaining your ATV yourself and have to lift it quite often, it may be well-spent money to get a purpose-made ATV/motorcycle jack. But it is not mandatory for this inspection.

You want to make sure you don’t have any free play in the tie rods or the A-arms. Just grab them and feel by pulling in different directions. This may happen due to wear over time or bolts coming undone/loose.

Then see if all the bushings are securely fastened and not loose or worn in any way. The steering column bushing usually wears over time. The same goes for the ball joints on the tie end rods.

Tighten any loose bolts or replace worn parts. Worn components can soon break, so it’s never a waste to replace them, even if they are not why you ATV pulls to the side.

But remember that an ATV’s undercarriage is not entirely free of play even when the machine is brand new. Some small play may be perfectly normal and doesn’t necessarily mean you have to replace any parts.

You should also check for any wear in the wheel bearings or the bearings in the axle carrier. For the wheels, place on hand on top of the tire and on on the bottom and then try to wobble it back and forth to see if there is any play. For the carrier, grab the axle on both sides and check for play. Again I have to mention that even on a brand new bike, I have experienced just a small play when doing this test. So you shouldn’t expect it to be 100% tight and free of play!

Finish this point by greasing your undercarriage if your ATV has this option. Your user’s manual will give good instructions on what components should be addressed with the grease press. Usually, bushings and bearings, although some machines have sealed bearings that do not require service.

This often neglected maintenance is cheap and will greatly prolong your components’ life and prevent water from entering with rust development as a result.

Checkpoint three: Check for a bent or damaged undercarriage

Visually inspect the undercarriage components to identify bent or damaged parts.

The A-arms are especially prone to bending if you hit a stump or a rock while going off-road. The «fast-growing» trees that seem to pop up suddenly just in front of the ATV when you ride are the worst!

The A-arms are actually designed to be the part that breaks first to avoid damaging components that are harder or impossible to repair, like the ATV frame. But it is not always easy to see if they are bent or not. Some even come with a curve from the factory.

My best tip is to try to find an angle to compare them to the tie rods. If they are parallel on one side but not on the other, the arm is likely bent. This method is much easier on a snowmobile where you can stand on top of your machine and aim down on both A-arms at the same time to compare.

Also, check the shocks for any visual damage. If the ATV was tipped over, the steering column and/or tie rods could be damaged. If the bolts on your steering column make contact with nearby components at a full turn, it is likely bent. Steering hoops may also be bent, depending on how bad the rollover was.

Checkpoint three: checking the diffs and brakes

While your ATV is still jacked up, you may as well check if your diffs are healthy. If they are damaged, the power distribution might be off, sending all the power to one of the wheels, naturally causing a pull to one side.

It’s easy to test this. With the 4×4 engaged and the ATV in gear, try spinning one of the front wheels; if the other wheel spins freely in the opposite direction, then your diff is likely okay. Also, try this with the 4×4 disengaged.

Then put the bike in neutral and check that all four wheels spin freely with no brake drag or grinding sounds. If the brake is dragging on either side, you should address this.

Checkpoint four: Make sure your toe alignment is on track

The reason why I didn’t address misalignment before in this step is quite simple. I don’t want you to fall for the temptation to start making adjustments to the bike before you are sure that none of the above reasons cause your troubles.

Even tho making adjustments may improve the situation; even if your problem is one of the above, you are not addressing the real issue; you are just compensating without fixing what is really making your machine pull to the side.

Your rear tires should generally always be parallel to each other and perpendicular to the ground. The front tires, on the other hand, should be leaning slightly toward the ATV. This is called camber. They should also be angled slightly inward (toe-in) or outward (toe-out) depending on your intended use. Some riders even prefer parallel front tires.

On stock ATV suspension, you usually don’t have the option to adjust the caster and camber as you may have on a car. These are set at the factory and should normally not be an issue. This basically leaves just the ability to adjust the toe-in on your bike.

Most manufacturers strongly advise against owners making this kind of adjustment on their machines of their own. So in this article, I will not be addressing the alignment procedure itself; this will come in a separate article later.

But what you definitely can and should do, is to control if the toe alignment is set according to factory specifications. Your user manual usually has brand-specific instructions and recommended toe-in specs. The recommended specs vary depending on the intended use of the machine.

For sport type purposes, it is recommended to have a slight toe-in. This means that the distance between the rims’ front is slightly shorter than at the back, usually no more than 6-12mm. This gives a more precise and responsive steering response.

In racing, it is common to prefer a parallel adjustment of the front wheels to reduce drag and increase performance.

For utility ATVs, on the other hand, it is recommended with a slight toe-out. This means that the distance between the rims’ front is slightly longer than at the back, usually no more than 6-12mm. This setup makes the bike more stable, especially when carrying heavy cargo on the front rack.

Some riders use their utility ATV mostly for trail riding and prefer a slight toe-in for better handling.

This is how you check the tire alignment on any ATV

  1. Place your ATV on a hard level surface like a garage floor.
  2. Place the handlebars as if going straight ahead. Visual alignment is usually accurate enough. Optional, but important if you plan on making any adjustments yourself: Fasten each side of the handlebar to a fixed location at the back of the bike using tie-down straps to make sure it doesn’t move out of position.
  3. Tie a string between two stands and place the stands on one side of the ATV so that the string is parallel with and just barely touching the rear tire.
  4. Then measure the distance between the string and your rim at both the front and back of your front wheel. The difference between these two measurements should be the same on both sides of your ATV and according to factory recommendations.

If you don’t have a string and stand available, or if you want more accuracy, use this method:

  1. Measure the distance from the ground to the wheel’s center to find half the tire’s height.
  2. Use this measurement to mark off four measuring points on the inside of the wheels. You’ll need one mar in front of the axle and one behind the axle, both at the same distance from the ground.  I prefer placing the marks on the rim and not the tire for the best accuracy.
  3. Then measure the distance between the two front marks and then the rear marks. Compare the measurements up against your desired specifications.

Checkpoint four, low-quality tires

If you still have stock tires on your quad, they are not always the best quality.

They may seem perfectly fine, but manufacturers often choose cheap tires to keep the bike’s price as low as possible. Also, they know that changing to better tires is often one of the first upgrades people do to their ATV, so no need to break the budget on tires that will be replaced anyway.

Upgrading to a decent aftermarket tire may vastly improve your machine’s riding performance and may also eliminate any issues you have with pulling to the side.

Until recent years, almost all ATV tires were bias-ply tires. Keep in mind that this style of tires is not ideal for pavement use. They generally get warmer when you ride and are less resistant to wear.

If you have any abnormal or uneven wear in your tires, this will most likely affect the ability to go in a straight line on a paved road. If you ride mainly on hard, smooth surfaces, you may want to consider investing in some radial tires instead.

When buying new tires, you can test them when they are brand new with the method in checkpoint one. If they don’t have close to identical circumference when tire pressure is the same, I would take them back to the dealer and ask for a new set or consider a different make and model.

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I'm an ATV and offroad-enthusiast, an engineer, a farmer, and an avid home-mechanic. I'm also the owner and editor of BoostATV.com. If you have any questions or suggestions regarding this article, please feel free to contact me.