It’s hard to judge the correct tyre pressure without a gauge, but as a quick estimate a tyre should feel as firm as an apple and not as squidgy as an orange. This is probably a lot firmer than you’d expect. Many of the tyres we see are under-inflated. The correct tyre pressure will be written on the sidewall of the tyre and will say something like “Inflate to ??”, and that number will be stated in PSI or Bar. BMX and mountain bike tyres are about 40psi, and road tyres can be upwards 100psi. Both pressures are very hard to achieve with a normal hand pump, so it’s easiest to use a track pump with a pressure gauge or a car foot pump. You can also pop into your local bike shop and use theirs.
Correctly inflated tyres will last longer and give better performance. You can easily spot tyres that have been under-inflated for a long time as the rubber is cracked or split.
Types of Valve
There are two main types of valve that you are likely to encounter (on a modern bike): Presta and Schrader. Both should have a dust cap on top to keep out dust and debris.
The Presta type has a little knurled nut on the top, which can be unscrewed to allow the top to be depressed to let out air. The Schrader valve is the same you get on cars and needs a screwdriver or thin implement to push in the valve to let out air. Sometimes the Presta valve can stick a bit, so unscrew it and let a tiny amount of air out. This will free up the valve before you start inflating.
It’s important to know the type you have so you can buy a pump with the correct fitting. Some pumps come with a universal fitting that works with both, and some have a “dual-head” – two holes at the end and some sort of switch to engage the correct one.
Types of Tyre
This is a tricky subject so we’re going to generalise. A lot!
Mountain Bikes generally have fat, knobbly tyres and Road bikes are generally thinner with smoother tread. Smoother tyres are faster; knobbly tyres have more grip on rough ground. Road tyres are run at high pressure, whereas bmx and MTB tyres are lower pressure. Tyres on hybrid bikes fit somewhere in between.
Sizes of Tyre
There are two measurements to consider, and these are nearly always embossed into the side-walls of your tyre in the format A x B. For example: 700 x 23 or 27.5 x 2.25 or 16 x 1.5
The first measurement is the diameter of your wheels, and you must get this exactly right if you are changing or renewing. Road tyres are often 700c; MTB tyres range from 26″, 27.5″ and 29″. Kids bikes usually have smaller tyres than this.
The second measurement is how ‘fat’ the tyre is, and you have a bit of leeway with this. Fatter tyres are generally heavier but more comfortable, but there’s a big debate about which is best – both for road and off-road.
Unless you’re sure what you need it’s best to visit your local bike shop.
Which Tyres do I need?
Bikes these days are extremely capable machines, so there’s a lot of cross-over on where people take them. You can therefore get a wide variation in tread patterns. There are also options for better puncture resistance, lower weight, tubeless, etc…
If you’re not sure then pop into your local bike shop and get some advice. The question you need to answer is: where do you ride most, e.g. on the road; commuting; on cycle tracks; in a forest; over the Downs; a bit of everything.
Cycling UK have an explanation of tyre sizes HERE.
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