Ask Levi: Should I Have Two Matching Tire Sizes On My Bike?

Most new bikes come with the same size tires on the front and back. But that doesn’t mean you can’t change things up. Here’s why you might want to run different tire sizes – or two completely different tires – on the front and back of your bike.

Should I Have Two Wide Tires On My Mountain Bike?

This article was inspired by a reader’s question about using different width tires on your mountain bike and why that might be a good idea…

My mountain bike has a 2.5 tire on the front and a 1.95 on rear. Should I put a 2.5 on the rear?

I just bought the bike – its an older, short travel full suspension. I’ve not had this tire setup before and am looking for input. What is to be gained from this setup? Should I just match em up?

Thanks,
Mismatched Michael

Hi Michael,

A narrower rear tire like you have is a common setup for mountain biking. Since you bought the bike used, I’m betting it originally came with 1.95″ tires front and rear. That would have been typical for that style bike.

What most likely happened is that the previous owner wanted to run larger tires, and he probably put on the biggest tires that would fit the bike. The frame could probably only handle a 1.95″ or maybe a 2.1″ as the rear tire. However, most any front fork can accommodate a larger front tire, around 2.2″ to 2.5″ wide.

So the question isn’t really “why a smaller rear tire?,” but rather, “why a larger front tire?”

Narrow Rear Tire + Wide Front Tire

Running a narrow tire on the rear wheel and a wider tire up front makes a lot of sense.

Here are the reasons you might run a narrow rear tire and wide front tire on your mountain bike:

• Increased Traction – The front tire is extremely important when it comes to traction, especially when turning. In most cases, a wider tire will provide better traction, so it makes sense to run a larger front tire. (While you still need traction from the rear tire, it’s usually not a big deal when the rear tire loses a little traction. However, if the front tire loses traction, you could be in big trouble!)
• Softer Ride – A wider tire holds a greater air volume, which means you can safely run slightly lower tire pressures. The lower pressure will make for a softer, more comfortable ride. With a hardtail or older short-travel full suspension bike, you probably want the softest ride possible! (Lower pressure will also help increase traction.)
• Weight – The wider the tire, the heavier the tire will be. Running two wide tires will significantly increase the rotating weight on the bike, requiring more effort to ride fast. Sticking with only a wide front tire is a good compromise. The narrower tire on the rear wheel will make it easier for you to get up to speed.
• Rolling Resistance – Contrary to conventional wisdom, wider tires have less rolling resistance compared to a narrow tire. A narrow tire may have less air resistance, but at the speeds you often encounter mountain biking, aerodynamics are less important.
• Frame Limitations – While there is generally quite a bit of room in the front suspension fork (a 2.3-2.5 tire can probably fit), the frame can only accommodate a certain size tire. On the typical cross country mountain bike from the 90’s or early 2000’s, you won’t get bigger than a 2.1 tire back there.

As you can see, wider tires are better in most situations. But if a wide tire won’t fit your bike, you’re forced to use a narrower tire.

Tire Choice Depends on Many Factors

As you can see, tire size is about compromise. The narrow tires are light, but going with a wider tire will increase traction and comfort.

The narrow tire in the back and a wider one up front makes for a pretty good compromise between weight savings, comfort, and traction.

In general, I used to run 2.1″ tires front and rear on my hardtail and short-travel XC racing bikes. These days, I’m usually running 2.2″ or 2.3″ tires on my full-suspension 29er.

However, if you’re out having fun on the trails and not so worried about your top speed, go wide. The 2.5″ front tire will probably be nice. So you can definitely stick with the tires you have.

There’s no real downside to running different tire sizes, so there’s not much reason for you to change anything. For example, there’s no need to carry different size spare tubes. A 26×1.95 tube (you could probably find one marked “fits 1.95-2.2 tires”) will fit just fine in a 26×2.5 tire.

Now if you decided to run a 1.25″ slick tire on the rear and keep the 2.5″ knobby tire up front… then you might need to double up on spare tubes!

And you could always convert to a tubeless setup using Stan’s rim strips and sealant! That would give you an even better ride, and there would be less worry about ever using a spare tube!

You Can Use Completely Different Front and Rear Tires

Now you might be thinking, “What if I put two completely different tires on my bike?”

That is absolutely fine!

There is no harm in having different tire sizes, different tire models, or different tire brands used together.

In fact, the demands placed on front and rear tires are so different, that some manufacturers have front-specific and rear-specific tires. This allows them to design the tread pattern specifically for the demands of either the front wheel or rear wheel.

It can be beneficial to use different tires front and rear!

Even for Road Bikes?

The same holds true for road bikes. Wider tires provide better grip and a smoother ride, but frame limitations prevent you from using wide tires.

Now, most modern road bikes do allow for wider tires than the 23-25mm sizes that were common years ago. You might be able to run 700×28 tires!

(And yes, the same rules apply in terms of different sizes, types, and brands – feel free to use them interchangeably.)

By Coach Levi on May 6, 2010   /   Mountain Biking Articles, Mountain Biking Tips   /   5 Comments

Tags: tire size, tires