Installation of larger tires is among the most common modifications undertaken by ATV owners. The primary motivation for most riders is to enhance off-road performance. Some opt for this modification for aesthetic appeal, while others aim to boost their vehicle’s top speed.
But bigger is not always better when it comes to tires and speed. So do bigger tires make an ATV faster?
Installing bigger tires on an ATV can increase the top-end speed when riding on a straight flat. But it will also negatively affect low- and mid-range acceleration and handling, making the bike slower in most riding situations. It will add more stress to the bike suspension and drivetrain.
Taller Tires Tire Can Increase Top-End Speed (In Theory)
In the context of ATV tires, ‘bigger’ usually refers to tires that are wider and have a larger diameter than the original ones being replaced. This is often described as a ‘taller’ tire, measured from the ground level to the top of the tire.
Installing a taller tire will increase the ATV’s effective gear ratio due to the tire’s more extended circumstance. For each axle rotation, the bike will move a bit further.
A 26-inch tall tire has a circumstance of 81,6 inches, while a 28-inch tire measures 87.9 inches. This means the larger tire moves 6.3 inches farther than the smaller tire each time the axle turns.
As long as the ATV has the engine power required to keep up, a bigger tire will increase the bike’s top speed, at least in theory. As speed increases, so will wind resistance and drag.
Smaller and medium-sized ATVs will not always have adequate horsepower to increase speed over a certain point. Where this line goes varies from model to model.
Bigger Tires Cause Power Loss
Generally, bigger tires tend to be heavier, at least when comparing different sizes of the same brand and model tire.
The increased mass of bigger tires requires more engine power to initiate movement due to the enhanced rotational mass. Additionally, these tires create a higher effective gear ratio, as previously discussed.
These factors increase engine strain, decreasing low-end torque and slowing acceleration.
Interested in knowing the lightest mud tire? Check our ATV Mud Tire Weight Comparison (With Charts).
Bigger Tires Are Harder to Spin in the Mud
Massive mud tires are a must to get through the gnarliest mud pits, but they rob a lot of horsepower.
Unless you have made the necessary modifications to accompany your bigger tires, the ATV will likely have difficulty maintaining the same speed through the mud as it did before.
Poorer Handling Will Make Cornering Slower
Most people install bigger tires on their ATVs to improve off-road performance by increasing ground clearance.
But with a higher ground clearance comes a higher center of gravity. A higher center of gravity will leave the ATV more unstable and likely to tip when cornering at high speeds. You cannot corner as fast as you were with stock tires.
Bigger and heavier tires are also harder to steer, making the ATV less agile and maneuverable on the trails. This also negatively impacts how fast you can ride.
How to Maintain Acceleration, Speed, and Handling When Installing Bigger Tires?
We’ve examined how installing bigger tires can negatively affect acceleration, low-end torque, and handling. Luckily there are ways to reduce these downsides of modifying the ATV.
The problem can be knowing what modification you need for your specific setup. To answer this question, you need to ask yourself what type of riding you do the most.
A stock ATV is tuned for good performance in many riding applications. Some like slow and torquey rock crawling, while others like high-speed trail riding or dune racing. An ATV set up for speed is not ideal for crawling and vice versa.
Also, you must consider how much bigger the tires are from stock. A slight increase in size does not require the same modifications as a massive increase.
There are many opinions on this topic, and no definite answer fits all. But to give you a general idea, here are some general guidelines I’ve learned from reading and watching the content of some of the major players in the business.
The Average Rider That Increases Tire Size by One Inch
This is your typical ATV owner that uses his ATV for a wide range of riding applications but wants to go up one inch in tire size for a slightly better grip and flotation.
Recommended modification: None
Generally, you can increase the tire diameter by one inch without modifying the ATV’s drivetrain. Most ATVs will have enough space in the wheel wells to allow one inch bigger tire without getting rubbing issues.
Already at one inch bigger tires, you will start noticing some of the adverse side effects of a bigger tire on low and mid-range performance, but not more than what is acceptable to most people.
High-Speed Riders With Two or Three Inches Bigger Tires
This category covers those that enjoy dune racing, high-speed trail riding, or mud pit bashing. A tire size increase of two to three inches considerably impacts the low and mid-range performance. You may struggle to reach the RPM levels at which the engine delivers optimum performance.
Recommended modification: Install a clutch kit
A clutch kit will be the best option for those with a maximum of two to three inches increase in tire size from stock and who like to go fast.
Installing a clutch kit on your ATV will compensate for the power loss and slow response you get from installing bigger, heavier tires. It will improve low and mid-range acceleration, and a quicker backshift will give you a crisper throttle response.
You can see it as a recalibrating of the clutch to compensate for the gear ratio shift due to the larger tires.
This is achieved by optimizing and controlling at what RPM the clutching phase happens. That is when the belt travels from the bottom to the top of its travel on the primary clutch.
In other words, you are increasing the engagement RPM, typically from 1900 to 2100 or 2300, depending on what spring weight you choose. This will make sure you stay in the engine’s power band.
A clutch kit contains stiffer springs and lighter clutch weights. It is not recommended to use one without the other.
Note that you will lose a few mph of top speed with some clutch kits when running stock tires, but some may even get an increase in top speed due to lighter clutch weights.
Look for a quality kit that is specifically made for your vehicle. A flexible kit will work well with both stock and bigger tires without a significant top-end speed loss.
A quality clutch kit from leading providers like Dalton or EPI will set you back around $300, which is not bad considering the benefits.
Check this video to learn if you need a clutch kit or not:
Slow-Speed, High Torque Riders With Two or Three Inches Bigger Tires
These are the typical rock crawlers that do a lot of technical riding that requires a lot of torque and belt grip at slower speeds.
As soon as you go up two to three inches or in tire size, you notice a significant loss in low-end grunt due to the extra tire weight and a gear ratio that is off.
Running at low speeds will add a lot of extra strain on the drive belt as it cannot position itself properly on the clutches. The belt will heat up and wear out much faster than usual.
Recommended modification: Gear reduction kit
Those that prefer high torque, slow speed technical riding will likely be better off choosing a gear reduction kit over a clutch kit.
A clutch kit is not ideal for this riding style, as it won’t give you the necessary belt grip.
You may benefit from a gear reduction even with stock tires, as even the low-range gearing is a bit high for rock crawling on most ATVs.
With a gear reduction kit, you will allow the stock clutches to operate where it performs best, even at slower speeds. It will take some of the load off the clutch and belt, making it easier to turn tires, axles, etc.
There are two main types of gear reduction kits to look into:
- Portal gearboxes, one for each wheel. This option is likely the best for those that ride slowly.
- Internal transmission gear reduction. This option is likely best for those that run massive tires but like to go fast.
Check this video by Hunterworks Inc to learn more about the difference between clutch kits and gear reduction kits.
High and Low-Speed Riders With More Than Three Inches Bigger Tires
When increasing the tire size even further, the gear ratio will be way off, leaving the engine and transmission unable to keep up. You will begin burning belts regularly, especially when riding at lower speeds.
Recommended modification: Clutch kit and Gear reduction kit
When increasing the tire size by more than three inches from stock, you should consider getting both a clutch kit and a gear reduction kit.
There is a limit to how much of an increase in tire size a clutch kit will handle before you reach the point of diminishing returns. With massive tires, you may need a gear reduction kit to take some of the load of the clutch and belt.
While gear reduction is ideal for slow-speed riders at any tire size, it may also benefit high-speed riders that run massive tires.
Installing Wheel Spacers Can Make the ATV More Stable
Wheel spacers will not only give you better clearance that allows for installing wider tires or installing chains on stock tires. They will also improve the stability of the ATV, effectively reducing the rollover rate.
Also, the extra ground clearance gained from installing bigger ones makes the vehicle more susceptible to tipping, especially when cornering. Wheel spacers will move the tires outward, effectively improving the sideways stability of the ATV.
Remember that wheel spacers will increase the stress on wheel bearings and joints. Therefore it is not recommended to install thicker spacers than necessary to achieve the required clearance and stability. ½ inch up to two inches are the most common thicknesses used for ATVs
Check this post to learn more about the pros and cons of ATV wheel spacers or how to choose the right wheel spacers for your ATV.
Other Potential Downsides of Installing Bigger Tires
Increased Drive Belt Wear
The added strain on the original clutch setup will increase heat buildup and belt wear.
A clutch kit will optimize the gear ratio, reducing belt slip and clutch heat buildup. But even with a clutch kit, the OEM belt may not handle the added strain caused by bigger tires.
Consider getting a heavy-duty or severe-duty drive belt specifically made to handle larger tires and aftermarket clutch kits. I recommend reading this post if you’re having problems with your ATV belt slipping.
Premature Driveline and Wheel Bearing Wear and Failure
Due to the increased angles and extra weight, the CV joints, U-joints in the axles, and A-arm bushings will wear much faster. The CV joints may snap straight off on your first ride running bigger tires.
To encounter this issue, you need to install heavy-duty wide-angle axles.
The added stress of bigger tires will also make your wheel bearings wear out faster than stock tires. If you regularly drive in deep mud, I recommend getting a wheel-bearing greaser to prevent water from getting into the wheel bearings, causing rust and even faster wear.
Tire Rubbing on Suspension, Brake Lines, or Body Panels
Most ATVs will handle one-inch bigger tires without any rubbing issues.
But with even bigger tires, you may need a set of wheel spacers and do some fender cutting to provide enough space for the extra rubber.
It May Void the Manufacturer’s Warranty
Many manufacturers impose restrictions on increasing tire size due to the additional stress it places on the ATV’s driveline and suspension, as doing so may void the warranty.
You may be allowed to go up one or potentially two inches, but to be sure; I recommend you ask your dealer in advance.
There Are Better Ways to Make Your ATV Go Faster
If your sole goal is increasing acceleration or top-end speed, some options may be better suited than installing bigger tires.
If maximum acceleration is your top priority, you will be better off going down a size from your stock tires.
The reduced effective gear ratio will improve low-end torque and acceleration, leaving your competition behind on the drag strip.
The Bottom Line
While installing larger tires on an ATV can theoretically increase the vehicle’s top-end speed, it’s important to consider the various factors at play.
Oversized tires can negatively affect acceleration, handling, and overall performance, especially without proper modifications to the drivetrain or suspension.
Therefore, it’s crucial to understand your riding needs, the specific characteristics of your ATV, and how modifications might impact its performance before deciding to install larger tires.