Which tyres should I put on my bike?

Tyres are the cheapest change that alters how a bike rides. They are also the component people leave alone for years, running whatever came on the bike on surfaces it was never meant for. Three decisions cover it: how wide, how much tread, and how much protection.

What you'll need

• The size printed on your existing tyre sidewall
• A tape measure or a coin to check clearance

Step by step

1. Read the size on the sidewall.Modern tyres carry an ISO or ETRTO size such as 32-622: the first number is the width in millimetres and the second is the bead diameter. 622 is what most people call 700c, 584 is 650b, 559 is 26 inch. The bead diameter must match your rim exactly; only the width is a choice.
2. Check what will actually fit.Look at the gap between the current tyre and the frame, the fork crown, the chainstay bridge and the brakes. You want clearance for the wider tyre plus room for mud and a mudguard if you use one — a good rule is enough space to slide a pound coin between tyre and frame. On rim brakes, the brake arch is usually the limit.
3. Choose the width for the surfaces you ride.Smooth tarmac and fast riding: 28 to 32mm. General road and towpath commuting: 32 to 40mm. Gravel, forest track and rough lanes: 40mm upwards. Mountain biking: 2.2 to 2.5 inches. Wider tyres at lower pressure are more comfortable, grip better on poor surfaces and are barely slower.
4. Decide about tread honestly.On tarmac, tread does nothing useful — a bicycle tyre cannot aquaplane at any speed you can pedal, and a slick has more rubber on the road. Knobs are for digging into loose surfaces: mud, gravel, grass, snow. Fitting knobbly tyres for road use costs speed and grip and buys nothing.
5. Decide how much puncture protection you want.A protection belt under the tread adds weight and stiffness and costs a little speed, and if you commute through glass, hedge cuttings and flints it will save you far more time than it costs. Heavy-duty commuting tyres are close to unpunctureable and feel like it.
6. Match the front and the rear sensibly.The rear carries more weight and wears far faster; the front does most of the steering and braking. A common approach is to fit the tougher tyre at the back and the grippier at the front, and to move a part-worn rear tyre nowhere — worn tyres go in the bin, not onto the front.
7. Set the pressure for the tyre and your weight.The number on the sidewall is a maximum, not a recommendation. Wider tyres want much lower pressure than narrow ones, and heavier riders want more than lighter ones. Too hard is the most common error and it makes the bike slower and rougher.
8. Check the folding versus wire question.Folding tyres have a Kevlar bead: lighter, more expensive, and they pack into a saddlebag as a spare. Wire-bead tyres are cheaper and perfectly good for everyday bikes.

Tips

• Fitting the widest tyre your frame will take, at a sensible pressure, is the single most effective comfort upgrade on most bikes.
• Check the tyre's direction arrow when fitting, if it has one, and put the label at the valve so you can find the corresponding spot in the tyre when hunting a puncture cause.
• Replace a tyre when the tread is worn flat, the casing shows through, or the sidewall is cracked or bulging. A bulge means the casing has failed and the tyre can blow off the rim.
• Keep the old tyre as an emergency spare only if it is sound. A worn-out tyre is not a spare, it is the reason for the next puncture.

Common mistakes

• Fitting knobbly tyres to a road or hybrid bike for grip — They have less rubber in contact with tarmac and grip worse, not better, while making the bike slow and noisy.
• Buying by the inch measurement alone — Nominal inch sizes are not consistent between standards. Match the ISO bead number — the 622, 584 or 559 — and there is no ambiguity.
• Running the maximum sidewall pressure — That figure is a safety limit for the casing, not a target. At real-world weights, pressures well below it are faster and far more comfortable.

Alternatives

• Winter or studded tyres: Metal-studded tyres transform riding on ice and are useless and noisy on clear tarmac. Worth having on a second wheelset if you ride through hard winters.
• Semi-slick: Smooth centre for rolling on tarmac, tread at the shoulders for loose ground. A sensible compromise for towpaths and mixed routes.
• Balloon or cargo tyres: Very wide, moderate pressure, high load rating — the right answer for a heavily loaded bike or a cargo bike.

Questions people ask