Trailer and caravan tyre pressure guide
What tyre pressure should a trailer or caravan use?
Trailer and caravan tyre pressures are typically much higher than passenger car pressures — commonly 3.5 to 5.0 bar (51 to 73 PSI) compared to 2.0 to 2.8 bar for a car. The correct pressure for a trailer tyre is determined by the tyre's load rating (load index) and the actual load being carried, not by any vehicle OBD system or generic guideline. Trailer tyres are often narrow relative to the load they carry, requiring high pressure to support the weight. The specification is found on the tyre sidewall (maximum pressure) and in the trailer or caravan owner manual. A critically important distinction: the maximum pressure on the tyre sidewall is the absolute limit, not the target inflation — the target is the manufacturer-specified pressure for the actual axle load. Most caravan manufacturers specify 3.5–4.5 bar for standard leisure trailers. Under-inflated trailer tyres overheat rapidly, especially on motorways, and are the most common cause of caravan tyre blowouts.
- Trailer and caravan tyre pressures are typically much higher than passenger car pressures — commonly 3.5 to 5.0 bar (51 to 73 PSI) compared to 2.0 to 2.8 bar for a car.
- The correct pressure for a trailer tyre is determined by the tyre's load rating (load index) and the actual load being carried, not by any vehicle OBD system or generic guideline.
- Trailer tyres are often narrow relative to the load they carry, requiring high pressure to support the weight.
FAQ
- What tyre pressure should a trailer or caravan use?
- Trailer and caravan tyre pressures are typically much higher than passenger car pressures — commonly 3.5 to 5.0 bar (51 to 73 PSI) compared to 2.0 to 2.8 bar for a car. The correct pressure for a trailer tyre is determined by the tyre's load rating (load index) and the actual load being carried, not by any vehicle OBD system or generic guideline. Trailer tyres are often narrow relative to the load they carry, requiring high pressure to support the weight. The specification is found on the tyre sidewall (maximum pressure) and in the trailer or caravan owner manual. A critically important distinction: the maximum pressure on the tyre sidewall is the absolute limit, not the target inflation — the target is the manufacturer-specified pressure for the actual axle load. Most caravan manufacturers specify 3.5–4.5 bar for standard leisure trailers. Under-inflated trailer tyres overheat rapidly, especially on motorways, and are the most common cause of caravan tyre blowouts.
- What should I verify before using this information?
- Use TireFitLab values as a sizing reference, then verify the vehicle handbook, tire placard, rim compatibility, load rating, and physical clearance before fitting.
Why trailer tyre pressure is much higher than car tyre pressure
A car tyre is wide relative to its load — a 225/45 R17 tyre on a 1,500 kg car has a large contact patch and is inflated to around 2.3 bar. A trailer tyre carries a similar load on a much narrower tyre (195/70 R14C), which must be inflated much harder — typically 3.5–5.0 bar — to carry the weight without the sidewall collapsing.
The load index on a trailer tyre defines its maximum carrying capacity at maximum inflation. Running below maximum pressure reduces load capacity significantly — a tyre rated for 730 kg at 4.5 bar may only safely carry 450 kg at 3.0 bar. Since most caravans and trailers run near their axle limit, under-inflation is immediately dangerous.
A further complication: trailer tyres are often left unused for months, developing flat spots and slow valve leaks. Unlike car tyres checked constantly by the driver's feel, trailer tyre deflation is not noticed until it has become severe — or until the tyre fails on the motorway.
Correct pressure by trailer type
The following are typical ranges. Always verify against your specific trailer manufacturer handbook and the tyre sidewall maximum pressure. These are guides — the handbook takes precedence.
| Trailer type | Common tyre size | Typical pressure range | Notes |
|---|---|---|---|
| Small single-axle box trailer (750 kg GVW) | 145/80 R13 or 155/70 R13 | 3.5–4.5 bar (51–65 PSI) | Narrow tyre carrying full load — must be inflated to maximum or near-maximum. Check tyre sidewall for maximum pressure and set to that value unless manufacturer specifies lower. |
| Standard leisure caravan (1,100–1,500 kg GVW) | 185 R14C or 195/70 R14C | 3.5–4.0 bar (51–58 PSI) | Most UK and EU leisure caravan manufacturers (Bailey, Swift, Coachman, Hobby, Knaus) specify 3.5–4.0 bar. Always check your specific caravan handbook. |
| Large twin-axle caravan (1,500–2,000 kg GVW) | 195/75 R16C or 205/75 R16C | 4.0–4.5 bar (58–65 PSI) | Higher gross weight and often narrower aspect ratio tyre requires higher pressure. Bridgestone, Continental, and Michelin publish load-pressure tables for C-class tyres. |
| Horse box and livestock trailer (2,000–3,500 kg GVW) | 195/75 R16C or 225/75 R16C | 4.5–5.5 bar (65–80 PSI) | Higher GVW and dynamic load shifting from live cargo requires firm pressure. Always check axle load rating. Payload can shift dramatically when animals move. |
| Boat trailer (varies widely) | 165 R13C to 215/75 R16C | 3.5–5.0 bar depending on tyre size and boat weight | Boat trailer tyres spend long periods unused, which accelerates cracking. Tyres over 5 years old on a boat trailer should be replaced regardless of tread. Inflate to maximum when the boat is loaded. |
| Car transporter trailer (3,500+ kg GVW) | 225/75 R16C or 235/75 R17.5 | 5.0–7.5 bar (73–109 PSI) | Near-commercial vehicle territory. Requires commercial tyre specifications. Not applicable to a standard car towbar — requires an O1/O2 trailer licence in many jurisdictions. |
Load-dependent pressure — should you reduce pressure for a light load?
For car tyres, manufacturers sometimes specify different pressures for partial vs full load. For trailer and caravan tyres, the standard advice from Alko, BPW, and most caravan manufacturers is: inflate to full laden pressure at all times, regardless of current payload.
| Load level | Load (approximate) | Recommended action |
|---|---|---|
| Empty (no load) | 0 kg payload | Do not reduce pressure from the laden specification. Running empty is a significant part of total trailer mileage. Pressure reduction for empty running is not recommended — the risk of forgetting to re-inflate before loading is too high. |
| 25% of GVW capacity | Light load | Use full laden pressure. Trailer tyre pressure should not be adjusted for load variation below GVW — leave at manufacturer specification. |
| 50% of GVW capacity | Half load | Use full laden pressure. The safety margin in over-inflation at low loads is preferable to under-inflation risk when load increases unexpectedly. |
| 100% of GVW capacity | Maximum rated load | Use the manufacturer-specified pressure exactly. Do not exceed the tyre sidewall maximum. Exceeding GVW simultaneously with maximum pressure risks structural failure. |
Six common trailer tyre pressure mistakes
| Mistake | What happens | Consequence | Fix |
|---|---|---|---|
| Using car tyre pressure | The tow vehicle's door sticker specifies pressures for the car's own tyres. Applying 2.3 bar from a car door sticker to a trailer tyre that requires 4.0 bar will cause severe under-inflation and overheating. | Tyre blowout — the leading cause of caravan accidents and motorway closures. | Check your trailer or caravan handbook for the correct pressure. The tyre sidewall shows the maximum — inflate to that unless the manual specifies lower. |
| Checking pressure when hot | Pressure rises 0.3–0.8 bar from cold to hot during motorway driving. Checking after a rest stop on a long journey and adjusting down to the "correct" specification means the tyre will be under-inflated when cold. | Under-inflation leading to excess heat generation and potential tyre failure. | Always check pressure cold — before departure, or after 3+ hours of rest. |
| Ignoring pressure for short trips | Many owners only check pressure at the start of the season. A slow valve leak or bead seep can lose 0.5 bar over 3–4 months without being obvious. | Arriving at the campsite to find both tyres at 2.8 bar instead of 4.0 bar. | Check before every trip regardless of distance. Trailer tyres are more vulnerable to slow leaks due to infrequent use. |
| Not checking spare wheel pressure | The trailer spare wheel (if fitted) sits unused for years. It slowly loses pressure — often to 0 bar if the valve degrades. | Blowout on the road with a flat spare. | Check spare at every pre-departure inspection. Include it in the monthly check. |
| Using nitrogen for a significant saving | Nitrogen is marginally slower to permeate than air, but trailer tyres experience much higher pressure losses from valve degradation and rim corrosion than gas permeation. | Nitrogen provides no meaningful benefit for most trailer applications. | Use standard dry compressed air. Spend the nitrogen cost on a quality pressure gauge and replace valves every 2 years. |
| Ignoring tyre age | A 9-year-old caravan tyre with 95% tread remaining is still a high-risk tyre. Trailer tyres experience significant UV and ozone degradation while parked outdoors for months each year. | Sidewall blowout from rubber degradation even at correct pressure. | Replace trailer tyres at 5 years regardless of tread. 7 years is an absolute maximum. Read the DOT date code to verify actual age. |
Tyre age and replacement intervals for trailers
Trailer tyres age faster than car tyres because they are stored outdoors (UV and ozone exposure), unused for long periods (UV exposure without the flexing that circulates antiozonants), and often lack the protective antiozonant chemistry of passenger tyres. A 6- year-old caravan tyre that has spent three summers in a field is equivalent in degradation terms to a 10-year-old car tyre.
| Tyre age (from DOT date code) | Risk level | Recommended action |
|---|---|---|
| Under 5 years | Low | Normal use. Inspect annually for cracking. |
| 5–7 years | Moderate | Inspect carefully at start of each season. Any Grade 2+ cracking: replace. Plan for replacement at next service. |
| 7–10 years | High | Replace strongly recommended regardless of tread. Caravan and motorhome manufacturers (Alko, BPW) recommend replacement at 7 years. |
| Over 10 years | Unacceptable | Replace immediately. Do not use on the road. |
For DOT code reading and crack grading, see our Tyre cracking and ageing guide and Tire age guide.
Valve types for trailer and caravan tyres
The valve is the most failure-prone component of a long-stored trailer tyre. Rubber valves degrade faster than the tyre and should be replaced at every tyre change and whenever the tyre is removed from the rim.
| Valve type | Typical use | Max pressure rating | Notes |
|---|---|---|---|
| Standard rubber Schrader valve (TR413) | Small trailers, boat trailers, 750 kg box trailers | 4.1 bar (60 PSI) | Most common on budget trailers. Fine for typical leisure trailer pressures. Replace every 2 years — rubber degrades during long outdoor storage. |
| High-pressure rubber Schrader valve (TR415) | Caravans, horse boxes, heavier trailers | 6.2 bar (90 PSI) | Required for pressures above 4.1 bar. Visually identical to TR413 but rated higher. Confirm with tyre fitter at next service. |
| Metal clamp-in valve (TR416) | Alloy wheel equipped trailers, performance applications | 8.3 bar (120 PSI) | More durable than rubber valves. Better for long storage periods — metal body resists weather degradation. More expensive but recommended for any trailer storing 6+ months per year. |
| TPMS valve (direct system) | Trailers with factory TPMS or aftermarket trailer TPMS | Matches tyre rating | The trailer car TPMS fitted to newer caravans (Alko iQ7, PressurePro, TYREDOG) uses TPMS-enabled valves. Not interchangeable with standard valves. |
Trailer TPMS — worth fitting?
Standard car TPMS does not monitor trailer wheels. Aftermarket trailer TPMS systems (PressurePro, TYREDOG, Alko iQ7) use external or internal sensors on each trailer wheel and alert the driver via a dashboard display or Bluetooth to the tow vehicle. At motorway speeds where a caravan tyre blowout is most dangerous, having 2–5 minutes of warning before the tyre fails completely can prevent an accident. The cost (€80–250 for a two-wheel kit) is small relative to the risk.
For a full explanation of TPMS operation and sensor types, see our TPMS guide.
Pre-departure checklist for towing
- Check all trailer tyre pressures cold (before moving the vehicle). Compare to handbook specification.
- Inspect all four tyre sidewalls for bulges, cuts, and cracking.
- Check tread depth — trailer tyres require a minimum 1.6 mm but aim for ≥ 3 mm.
- Confirm spare wheel is present and fully inflated.
- Check all four valve caps are present.
- Verify DOT date code — replace if over 5 years old or showing Grade 2+ cracking.
- If TPMS fitted: verify all sensors show current readings before departure. A sensor showing no data indicates a flat battery.
- Adjust tow vehicle rear tyre pressure to the towbar/towing specification (typically 0.2–0.5 bar higher than normal — check the vehicle handbook, not the standard door sticker).
More tools
- Tire pressure guide
- Cold tyre pressure guide
- Tyre pressure and fuel economy guide
- TPMS guide
- Tyre cracking and ageing guide
- Tire age guide
- Tyre inspection checklist
- Tire & wheel reference guides
Seasonal check
Planning a long summer drive?
Use the budget and running-cost tools before a trip, especially if the current tyres are worn or the replacement size changes diameter.
What changed
- Reviewed deterministic geometry, load/speed references, sitemap inclusion and localized page shell.