There are several reasons why you might want to change the size of the tires on your bike.
For example, narrower tires facilitate speed because they roll with less resistance, whereas wider tires give you grip for cornering and braking, especially when you’re off-road.
If you’ve never done this before and you don’t know what to look for, you’re probably wondering, “How do I know if I can even change the size of the tires on my bike?” We’re happy to report we have good news for you! By the time you’re done reading this post, you’ll know.
You can change the size of the tires on your bike, within reason. By “size,” we mean the width of your tires. If you try to change the diameter without also changing the rim, the tire and tube won’t fit, and you’ll run into problems.
Let us expand on this a little bit more. This way, you can be sure that you are changing bicycle tires correctly. If you do it wrong, you will end up with a bike that’s either unsafe to ride—or frankly impossible to ride.
Is It Possible to Change the Size of Your Bike’s Tires?
To the question, “Can I change the size of my bike’s tires?” there is a clear, resounding answer: “Yes, within reason.”
“Within reason” assumes that you want to put a slightly narrower or wider tire on the rim (the tube is a whole other story) rather than change the diameter.
On most bicycles, a rim of a certain diameter will work with a range of tires of different widths. As long as the tires you put on the rims are within that range, you shouldn’t have any problems.
If you’re not sure what tire widths your bike’s stock rims can fit, check the owner manual. It should tell you. If it doesn’t—or your bike’s fitted with aftermarket rims—google the make and model of the rims and go to the manufacturer’s website to find out.
Do You Also Have to Change the Rims?
The long answer short is “no, you don’t.”
Unless you also want to change the diameter of the wheels, that is.
As long as you’re trying to fit a tire within the range of widths supported by your bike’s rims, you won’t have to switch the rim out. The only thing that gets switched out is the tires, and potentially the inner tubes.
(Of course, if you choose rims with a different diameter, you will also have to change the tires of your bike. For the sake of brevity, we will cover this some other day and in a separate post.)
How Tire Width Affects the Ride
Knowing that narrow tires are usually mounted on road bikes and city bikes, and wide tires on mountain bikes and hybrid bikes, should you buy narrower or wider tires for your bike?
Narrow Tires for Speed
Narrow tires are lighter and more compact compared to wide tires. They have less rubber, thinner treads, and are inflated to a higher tire pressure, so they roll with minimal resistance.
If you fit your bike with narrower tires, you typically gain road feel and speed on paved roads and in good weather. But you lose puncture protection.
Wide Tires for Puncture Protection
Wide tires are heavier and denser compared to narrow tires. They have more rubber, bulkier threads, and are inflated to a lower tire pressure, so they roll with more resistance.
If you fit your bike with wider tires, you usually gain grip off-road, traction in bad weather, and improved puncture protection. However, you lose speed and road feel.
Matching Tire, Tube, and Rim
As a general rule of thumb, if you mount a narrower tire on a wider rim, the tire will be flatter and less round. The tire shouldn’t be too narrow as there will be increased risk of damage, to the tire, tube, and the rim, from bumps, potholes, and foreign objects.
Conversely, mounting a wider tire on a narrower rim provides less support for the tire when cornering. In tight corners, the tire can twist so much that it gets pinched, sometimes so badly that it blows out.
The width of the bicycle tire should ideally be 1½ to 2 times the width of the rim bed. Also, if you are considering mounting wider tires on your bike’s rims, check that the calipers have enough clearance to function properly.
Last but not least is the inner tube. All inner tubes have a strict diameter and a width range. When choosing a tube size, always stay in the middle of the range so that the tube doesn’t come out too big or too small for the tire.
When in doubt, go to the local bike store and discuss this with the mechanics. They’ve probably done this enough times to know what to consider and exactly what tire sizes would fit on your bike’s rims without causing problems.
Changing the Rims
There are times when, for one reason or another, you do want to change the rims.
When choosing a rim size, the main thing to keep in mind is that your bike’s fork is only designed for a certain wheel diameter (the “wheel” meaning the tire mounted on the rim and filled to the proper tire pressure).
Mount larger wheels, and the tires will catch on the fork or the rear triangle. Mount smaller wheels, and, on bikes with rim brakes, there’s a good chance that the brake pads will no longer line up with the wheel.
How much you can change the rims on your bike will be dependent on how your bike has been designed. There isn’t a universal answer here. Some bikes may not allow you to adjust the rims at all. Others will give you a good amount of leeway thanks to adjustable brakes, or the fork/triangle sitting fairly high.
The Bottom Line
So, there you have it. You have the answer to “Can I put bigger/smaller tires on my bike?”
As with any good question, the answer is, “it depends.” While you can adjust the width of your bike tire, you won’t be able to change the diameter of your tire unless you change the rim.
When changing the width of your tire, you do have some wiggle room. That said, it’s still a Goldilocks dilemma: You don’t want to go to narrow, as the tire won’t have good support, nor too broad, as it may stick out of the rim in corners and brush against the brake pads.
Cycling, at the end of the day, is all about balance. And the tires you mount on your rims are no exception. 🙂