Cyclocross/Gravel-Reifen

This depends on the terrain you ride and the limits of your bike in terms of tyre clearance. If you ride in gloopy, muddy trails, tyres at the wider end of the spectrum, 40mm+ should give more grip, depending on their tread (more spaced out knobbbles can help reduce mud clogging). Dry, hard packed gravel is fine with narrower tyres and less aggressive tread (such as small knobbles) because grip isn't as vital. Most gravel bikes can run wider tyres on 650b / 27.5" wheels compared to larger 700c wheels. The downside to fatter tyres is that they can feel slow on the road, worth considering if you ride mixed terrain routes.

Yes! Riding tyres with bigger, spaced out tread knobs can make riding on hard, dry, smooth gravel tracks or roads much more hard work. Likewise, using small knob, smoother tyres on muddy wet terrain can reduce grip and traction. Choose tyres which suit your usual rides or keep a spare set of tyres / wheels to swap depending on the terrain and weather. 

Yes. Road disc wheels and tyres will work with your gravel bike. As long as the wheels have the same axles (100x12mm & 142x12) they will work fine, many gravel bike riders have a road wheelset with fast road tyres for days on tarmac.

Most gravel bikes can run either 700c or 650b / 27.5 wheels, as long as the hub thru axles are the same (usually 100x12mm / 142x12mm). Smaller 650b / 27.5 wheels will result in slightly less clearance over rocky terrain. Most gravel bikes can accept wider tyres while running smaller 650b / 27.5 wheels.

No. Tubeless tyres take a bit of effort for setting up, they also need regular top ups of sealant. How often and how much sealant for the top-ups depends on the tyre volume and the temperature where you live.

While they do take a bit of effort to get set up, tubeless tyres offer a few very real advantages. Firstly, the sealant can plug  punctures without you even knowing about them - there are limits though, bigger holes will need a tubeless plug. Generally, having no inner tube reduces the weight of wheels, making for a more 'sprightly' ride and improving performance. Tubeless tyres can be run at much lower pressures (if you need more grip off-road for example) without risking pinch flat punctures.

However, tubeless isn't ideal for everyone. If you just want to hop on and ride, and maybe don't have patience for the inevitable initial 'letdowns' of tubeless, it might be better to stick to tubes.

Probably yes. While some lower air capacity tubeless tyres (road tyres for example) can be set up with a regular floor pump, tyres with a bigger air capacity volume (such as gravel and MTB tyres) will usually need a bigger blast of air to properly seat the tyre onto the rim.

Stick to recommended tyre pressures and avoid speeding up the wearing process by skidding and regularly loosing grip (although it can be fun...). Nice smooth roads tend to wear road tyres less

Check tyre size on the sidewall of the tyre. Most road, hybrid and gravel bikes are 700c diameter, so the tyre size would be 700 x the width of the tyre, a 25mm tyre, for example, would be 700 X 25.

No. Sometimes harder tyres are slower because they bounce around a lot more on rougher roads, trails and tracks. On perfectly smooth roads or in the velodrome, harder tyres are usually faster - however always inflate to manufacturers recommended pressures.

Firstly, think about where you inflate your tyres. Do you need to inflate in the garage before your ride? Or out on the roads / trails, for emergency punctures? Floor pumps are best for keeping at home and offer the quickest and easiest way to inflate tyres to the right pressure. Mini pumps are best for taking on your ride, to use in the event of a puncture.

Tubeless pumps have an extra capacity tank which can release a large volume of air in one go. This helps seat tubeless tyres onto the rim.

Check which type of valve your pump needs to fit. Presta valves are thinner and have a screw closure at the end of the valve. Schrader valves are like car valves, fatter with a metal pin closure system. There are lots of pumps that can do both valves, if you need both types for different bikes.