Why Does My Tyre Pressure Keep Dropping?
If you're constantly topping up your tyres, there's usually a specific reason. Here's how to identify the cause and fix it permanently.
When to Act Immediately
If your tyre loses more than 5 PSI in 24 hours, or if you notice a visible bulge or damage, stop driving and get it checked by a professional immediately. This could indicate a serious safety issue.
Common Causes of Repeated Pressure Loss
1. Slow Puncture
The most common cause of repeated pressure loss is a slow puncture. This happens when a small object (nail, screw, glass) penetrates the tyre tread but doesn't cause immediate deflation.
- • Signs: Pressure drops consistently over days or weeks
- • Location: Usually in the tread area, sometimes visible on inspection
- • Solution: Professional repair or replacement depending on location and size
DIY Check: Mix soapy water and spray it on the tyre. Bubbles will form at the leak site. Mark the spot and take it to a garage.
Emergency option: If you need to get home or to a garage, tyre sealant can provide a temporary fix for small punctures. Remember this is only a short-term solution.
2. Faulty Valve or Valve Core
The valve stem (where you attach the air pump) can develop leaks. This is often the easiest and cheapest fix.
- • Signs: Pressure loss is consistent, no visible tyre damage
- • Check: Spray soapy water on the valve - bubbles indicate a leak
- • Solution: Valve core replacement (£5-£10) or new valve (£15-£25)
3. Temperature Fluctuations
Tyre pressure naturally decreases as temperatures drop. This isn't a leak, but normal physics - cold air contracts.
- • Signs: Pressure drops in cold weather, returns when warm
- • Rate: Approximately 1 PSI per 10°F temperature drop
- • Solution: Top up pressure in autumn/winter, check monthly
Note: This is normal and expected. Always check pressure when tyres are cold for accurate readings.
4. Damaged Wheel Rim
Hitting a pothole or kerb can bend or crack the wheel rim, breaking the seal between tyre and rim.
- • Signs: Pressure loss after impact, visible rim damage, tyre bead separation
- • Check: Inspect rim for dents, cracks, or corrosion
- • Solution: Professional rim repair or replacement required
5. Natural Air Permeation
All tyres lose air slowly through the rubber itself - this is completely normal and not a fault.
- • Rate: 1-2 PSI per month is typical
- • Signs: Gradual, consistent loss over weeks
- • Solution: Monthly pressure checks and top-ups
How to Diagnose the Problem
- 1Check pressure when cold - Inflate to recommended pressure and note the reading
- 2Recheck after 24 hours - If it's dropped more than 2-3 PSI, you likely have a leak
- 3Visual inspection - Look for nails, screws, or visible damage in the tread
- 4Soapy water test - Spray on tyre and valve, bubbles show leak location
- 5Check rim condition - Look for dents, cracks, or corrosion on the wheel
When to Visit a Garage
- •Rapid pressure loss: More than 5 PSI in 24 hours indicates a serious leak
- •Puncture in sidewall: Sidewall punctures cannot be safely repaired and require replacement
- •Rim damage: Bent or cracked rims need professional assessment and repair
- •Multiple punctures: If you find several objects in the tyre, it may be time for replacement
- •Can't locate the leak: Professional garages have equipment to find hidden leaks
- •TPMS light stays on: After inflating correctly, if the warning persists, the sensor may need attention
Prevention Tips
- Check tyre pressure monthly to catch issues early
- Ensure valve caps are tightly fitted to prevent dirt and moisture ingress
- Avoid potholes and kerbs which can damage rims and tyres
- Have tyres professionally inspected during annual service
- Replace tyres before they become too worn - worn tyres are more prone to punctures
Related Guides
Tyre Sealant Guide
Learn about emergency tyre sealant for slow punctures - when to use it and what to expect.
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Search Your CarImportant Safety Notice
Tyre pressures shown on this site are general guides only. Exact pressures depend on your tyre size, load, speed rating and market. Always confirm your pressures using the sticker inside your car's door, your fuel flap or your official owner's manual before driving.