How To Measure Bike Tyre Size

Bike Tyres are hopefully the only contact point that your bike has with the ground, whether that’s gnarly off-road terrain or smooth tarmac. Bike Tyre sizes are important for a number of reasons, as well as fitting the wheel, the diameter and width of your bike tyre changes the way your bike handles and feels; tyres also have an effect on speed - as well as the amount of grip you have. Understanding tyre sizes not only allows you to replace the tyres on your bike when they are worn out but gives you a greater understanding when looking to trial different sizes.

The larger the diameter of a wheel, the larger diameter of the tyre is - larger wheels roll better over the ground and obstacles. The smaller the tyre and wheel, the easier it is to manoeuvre. Likewise, the narrower the tyre is, the quicker it is - the wider it is, the slower it is - but the grippier it is.The larger the diameter of a wheel, the larger diameter of the tyre is - larger wheels roll better over the ground and obstacles. The smaller the tyre and wheel, the easier it is to manoeuvre. Likewise, the narrower the tyre is, the quicker it is - the wider it is, the slower it is - but the grippier it is.The larger the diameter of a wheel, the larger diameter of the tyre is - larger wheels roll better over the ground and obstacles. The smaller the tyre and wheel, the easier it is to manoeuvre. Likewise, the narrower the tyre is, the quicker it is - the wider it is, the slower it is - but the grippier it is.

Determining the tyre size fitted to your bike is easy, and the tyre size - like car tyres, can be found on the sidewall of the tyre. Alongside this information, you can also expect to see the make and model of the tyre, as well as the manufacturer recommended psi.

Road Bike Tyre Sizes

The first number you will see on a road bike tyre or a gravel tyre - is the width of the tyre in mm. This is commonly 700mm or 650mm. The second number is the width of the tyre, which starts around 23mm and runs to 48mm. Metric sizes can also be found, including 700c or 650b.

Mountain Bike Sizes

Mountain Bike tyres start with a smaller number than road bike tyres, because they are sized in inches. The most common mountain bike tyre sizes are 29 inches, 27.5 inches and 26 inches. Fat bike tyres are either 26 or 27.5 inches, and kids' mountain bike tyres vary from 12 to 26 inches. The next number is the tyre's width, which varies from 18.55 inches up to 2.6 inches for standard mountain bike tyres. Fat bike tyres range from 3 inches up to 5.2 inches.

Mountain Bike Tyre Clearances

Although there are a few stipulations when it comes to clearance, you need to ensure that you have enough room and space between the arms of the fork, seat stays, and brakes (however, most bikes now have disc brakes) lastly, any tyre change needs to fit your wheels.