How to Choose Gravel Tyres: Width, Tread and Pressure
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Gravel tyres cover an enormous range. At one end you have semi-slicks barely distinguishable from a road tyre; at the other, treads that wouldn't look out of place on a cross-country mountain bike. Both get called gravel tyres, and picking the wrong end of that range makes for a miserable ride.
This guide covers what actually matters — clearance, width, tread, casing and pressure — and maps it onto the tyres we stock.
Start with what your frame will take
Before anything else, find out your maximum tyre clearance. Fit something wider than your frame allows and it will rub, pack with mud, or in the worst case stop the wheel entirely.
Where to find it: most manufacturers publish maximum tyre width in the frame's geometry chart or technical specification. Search your bike model and "tyre clearance". If nothing turns up, measure it.
How to measure: with the current tyre fitted and inflated, check the gap between tyre and frame at the chainstays, the seatstay bridge and the fork crown. You want at least 6mm of clearance on each side — mud, grit and a slightly buckled wheel all need somewhere to go. Remember that a tyre's actual width depends on rim width: the same 45c tyre measures wider on a 25mm internal rim than on a 21mm one.
A note on the number on the sidewall. Tyre widths are nominal. A 700x40c from one brand can measure 42mm, and another 38mm. If you're right at the edge of your clearance, measure the fitted tyre rather than trusting the label.
Width: what it actually changes
Wider tyres run lower pressures. Lower pressure means the tyre deforms around obstacles instead of bouncing over them, which gives you more grip, more comfort and — counterintuitively — often less rolling resistance on rough ground, because energy isn't being wasted throwing you upwards.
The trade-off is weight, aerodynamics, and a slightly vaguer feel on tarmac.
| Width | Suits |
|---|---|
| 35–38c | Mostly tarmac with occasional gravel. Fast, light, limited comfort on rough surfaces. |
| 40–45c | The sensible middle. Handles tarmac well, copes with most gravel. If you don't know, start here. |
| 45–50c | Rough, loose or technical terrain, bikepacking with luggage, or anyone prioritising comfort. |
Most riders are best served by something in the 40 to 45 range. It's wide enough to be genuinely capable off-road without feeling sluggish on the road sections that link the good bits together.
700c or 650b?
Most gravel bikes run 700c wheels. Many will also take 650b, which is a smaller diameter rim that lets you fit a much wider tyre in the same frame — typically 47mm or more.
The result is a wheel of roughly the same overall diameter, but with far more air in it. Lower pressures, more comfort, more grip on loose surfaces. The costs are slightly more rolling resistance on tarmac and a second set of wheels to buy.
Worth considering if: you ride mostly rough surfaces, you're on a smaller frame where 700c wheels feel oversized, or you want a dedicated rough-stuff wheelset alongside a faster 700c pair.
Our Receptor comes in 650x47b as well as 700x40c, which is a size a lot of shops don't bother stocking.
Tread: matching rubber to surface
This is where most of the decision lies. Tread patterns run on a spectrum from near-slick to genuinely knobby.
Semi-slick
A smooth or lightly textured centre strip with defined shoulder knobs. Fast on tarmac and hardpack, with something to lean on when you corner. Poor in mud.
Best for: road-heavy riding with unpaved sections. Commuting on mixed surfaces. Dry, firm trails.
Ours is the Receptor.
Fast gravel
Small, closely spaced knobs across the whole tread. Still rolls quickly, but with grip available everywhere rather than only when leaning.
Best for: dry gravel, fire roads, hardpack. Racing. Riders who want speed but not at the cost of all traction.
Ours are the Reaver 700x40c and the Reaver 700x45c HYPR-X.
All-round gravel
Taller, more spaced knobs with ramped centre blocks so they still roll reasonably. The compromise choice, and the right one for most British riding.
Best for: mixed conditions. Riding where you genuinely don't know what's coming. Deeper or looser gravel.
Ours are the Rambler SilkShield and the Rambler Tanwall.
Aggressive
Square-edged centre knobs and oversized shoulder blocks with plenty of space between them, so mud clears instead of packing.
Best for: soft ground, mud, winter, and terrain that's really beyond what a gravel bike was designed for.
Ours is the Ravager.
Casing and TPI
TPI means threads per inch in the tyre's carcass. Higher numbers mean finer threads and more of them.
60 TPI uses thicker threads. More robust, slightly heavier, a firmer ride. Good where durability matters more than finesse.
120 TPI uses finer threads, so the casing is more supple. It conforms to the ground better, which means more grip and more comfort at the same pressure, and usually less weight. It's the better-riding option and it costs more.
Neither is wrong. A 60 TPI tyre on a bikepacking rig makes more sense than a 120 TPI race casing, because you care more about getting home than about the last few watts.
Sidewall protection
Sidewall cuts are the most common way a gravel ride ends early. The tread is thick; the sidewall isn't.
EXO is a cut and abrasion resistant fabric woven into the sidewall. Light and flexible enough that it doesn't deaden the ride. It's the standard choice.
SilkShield wraps protection from bead to bead, covering the tread area as well as the sidewalls. Heavier, more protective. Worth it on flinty lanes, farm tracks, and anywhere you're regularly finding sharp stones.
If you ride chalk and flint country — much of southern England — the extra protection earns its place.
Run them tubeless
If your rims and tyres support it, run tubeless. The benefits are real and there aren't many downsides beyond messier maintenance.
- Lower pressures without pinch flats, which means more grip and comfort
- Sealant handles small punctures while you keep riding, often without you noticing
- Slightly lower rolling resistance than a tube at the same pressure
Every gravel tyre we stock is tubeless ready. One warning: only use sealant in tyres designed for it. Putting sealant in a standard tyre will void the warranty and may not seal anyway.
Pressure: start here, then adjust
Pressure matters more than most people realise, and most riders run too much. These are starting points, not rules — adjust by feel.
| Rider weight | 40c | 45c | 50c |
|---|---|---|---|
| Under 65kg | 32–36 psi | 28–32 psi | 24–28 psi |
| 65–85kg | 36–40 psi | 32–36 psi | 28–32 psi |
| Over 85kg | 40–45 psi | 36–42 psi | 32–38 psi |
Run the front 2 to 3 psi lower than the rear — the rear carries more weight.
Adjust down if the ride feels harsh, you're bouncing on rough surfaces, or you're losing grip on loose ground. Adjust up if the tyre feels vague when cornering, you're hitting the rim on impacts, or you're getting sidewall squirm.
If you're running tubes, don't go below about 35 psi regardless of the table — pinch flats become likely. Never exceed the maximum pressure printed on the sidewall.
Do the front and rear have to match?
No, and there's a good argument for mixing. The front tyre does most of the work in a corner and is the one you really don't want to lose. The rear takes more wear and more weight, and a slipping rear wheel is recoverable.
A common setup is a grippier front and a faster-rolling rear. On our range, a Rambler up front with a Reaver behind gives you cornering confidence without the drag of running the more aggressive tyre at both ends.
Keep widths the same or go slightly wider at the front.
Tan wall or black?
Purely cosmetic. Tan sidewalls suit classic and steel builds and have become popular on gravel bikes generally. There's no performance difference. They do show dirt more.
Both Reavers and the Rambler Tanwall come with tan sidewalls; the Receptor offers tan in 650x47b.
Quick reference
| Tyre | Widths | Best for |
|---|---|---|
| Receptor | 700x40c, 650x47b | Road and hardpack, occasional gravel |
| Reaver Dual Compound | 700x40c | Fast, dry gravel. The lightest option |
| Reaver HYPR-X | 700x45c | Fast gravel with more grip and volume |
| Rambler SilkShield | 700x38c, 45c, 50c | Mixed conditions, maximum protection |
| Rambler Tanwall | 700x38c, 50c | Mixed conditions, lighter, tan wall |
| Ravager | 700x40c | Mud, soft ground, winter |
Still deciding?
Tell us what you ride and where, and we'll tell you what we'd fit. Send us a message with your bike, your usual terrain and your frame clearance if you know it. We'd rather help you get it right first time than process a return.