Tyre Pressure and Tread Depth: What the Rules Say

How we research

The legal minimum tread depth for a car tyre in the UK is 1.6 mm, and the Highway Code says tyres must be inflated to the vehicle maker’s specification [1][2]. This guide covers both, how to check them and what the penalties are, with the sources. It is guidance, not legal advice.

Last updated: 19 October 2026

Tread depth

  • The limit. The Highway Code says cars, light vans and light trailers must have a tread depth of at least 1.6 mm [1]. THINK! and GOV.UK give the same figure [2][3].
  • Where it applies. The tread must meet the limit across the central three-quarters of the breadth of the tread and around the entire circumference [1][3].
  • Other vehicles. Motorcycles, large vehicles and passenger-carrying vehicles need at least 1 mm. Mopeds need visible tread [1][3].
  • Why it matters. THINK! says driving with less tread can affect grip, braking distance and steering [2].

We could not open an official source for the 20 pence coin test, so we do not describe it here. A tread depth gauge gives you a number to compare with the limit.

A worked example

A tyre has a tread 195 mm wide. Three-quarters of 195 mm is about 146 mm, so the 1.6 mm minimum has to be met across the central 146 mm or so, all the way round. A reading of 2.0 mm in the middle of the tread is 0.4 mm above the limit, but the shoulders of the tyre are not covered by the rule. Measure at several points around the tyre, not just one.

Illustrative scenario: figures are examples, not quotes, valuations or market prices.

Tyre pressure

  • The rule. The Highway Code says tyres must be correctly inflated to the vehicle manufacturer’s specification for the load being carried [1].
  • How often. It says to check pressures weekly, before your journey, while the tyres are cold, because warm or hot tyres may give a misleading reading [1].
  • Where to find the figure. The Highway Code says to refer to the vehicle’s handbook or data [1]. GOV.UK also points you to your vehicle handbook for tyre information [3].
  • Why it matters. THINK! says underinflated or overinflated tyres can adversely affect braking distance, steering, fuel efficiency and the lifetime of your tyres [2].

Pressures are often given in bar or psi. One bar is about 14.5 psi, so 2.2 bar is about 32 psi. Check which unit your gauge uses against the figure in your handbook.

What illegal tyres can cost

  • THINK! says that if police stop you and find illegal tyres, you could receive a £2,500 fine and 3 penalty points per tyre [2].
  • GOV.UK’s vehicle check page says you can be fined up to £2,500, be banned from driving and get 3 penalty points for driving a vehicle in a dangerous condition [3].

The two pages word this differently, so we cannot say how the penalty is counted in every case. Check the current wording before relying on it.

Damage and age

The Highway Code says tyres must be free from certain cuts and other defects, and that some defects can attract penalty points [1]. It also gives age rules for some larger vehicles: tyres over 10 years old must not be used on the front axles of goods vehicles over 3.5 tonnes or passenger vehicles with more than 8 seats [1]. It does not give a maximum age for car tyres.

Recalls and safety

We searched the official recalls list for “tyre pressure” on 19 October 2026. It returned 57 reports, mostly bicycles and e-bikes. The ones that relate to inflating tyres include a recall of the Ring Automotive Cordless Tyre Inflator on 21 July 2025 and a recall of a bicycle floor pump on 21 November 2025 [4]. None of the first eight were tyres. Search the official recalls list for your inflator, gauge or tyre brand. Our product safety and recalls page explains how we check. Recalls checked 19 October 2026.

Questions people ask

1.6 mm across the central three-quarters of the tread and around the entire circumference [1][3].

How often should I check my tyre pressure?

The Highway Code says weekly, before a journey, while the tyres are cold [1].

Where do I find the right tyre pressure for my car?

The Highway Code and GOV.UK both point to the vehicle handbook [1][3]. We could not open an official source for other places such as door stickers, so check your handbook first.

Can I be fined for one bald tyre?

THINK! says the penalty is £2,500 and 3 penalty points per tyre [2]. GOV.UK describes a fine of up to £2,500 for driving in a dangerous condition [3].

Sources

  1. The Highway Code: Annex 6, Vehicle maintenance, safety and security, GOV.UK. Updated 22 October 2025, gov.uk. Checked 19 October 2026.
  2. Vehicle safety checks, THINK!, think.gov.uk. The page shows no date. Checked 19 October 2026.
  3. Check your vehicle is safe to drive, GOV.UK, gov.uk. The page shows no date. Checked 19 October 2026.
  4. Product safety alerts, reports and recalls, Office for Product Safety and Standards, GOV.UK. Searched 19 October 2026.