Snowdonia National Park — now officially Eryri — contains some of the most spectacular and demanding driving roads in Wales. From the Llanberis Pass to the Crimea Pass, these are roads that will expose any weakness in your tyres immediately. Whether you’re a tourist, a local, or a delivery driver on the A4086, this guide covers what you need to know.
Why mountain roads are harder on tyres
The roads through Eryri combine several demanding factors simultaneously: steep gradients, tight bends, variable surfaces (smooth tarmac, patched road, broken edge), and rapidly changing weather. Snow and ice can appear at altitude even in spring and autumn, while the valleys may be dry. Temperature drops significantly with altitude — roughly 0.65°C per 100 metres.
What to check before driving into Snowdonia
- Tread depth — minimum 3mm for mountain driving; 1.6mm is the legal limit but provides significantly less grip on wet or loose surfaces
- Tyre pressure — check cold. Don’t reduce pressure for grip; modern tyres are designed to run at their specified pressure
- Age — cracked or hardened rubber loses grip dramatically, especially in the cold. Any tyre showing sidewall cracking should be replaced before a mountain trip
- Spare or repair kit — mobile signal can be patchy on mountain roads. Know what kit you have before you go, not after a puncture on the Pen y Pass
Winter tyres for Snowdonia
If you regularly drive the A4086, A498, A470 or the Crimea Pass between October and March, winter tyres are worth serious consideration. They remain effective in temperatures below 7°C even on dry roads — their compound stays softer and grippier than summer tyres in the cold. A 3PMSF-rated tyre (three-peak mountain snowflake symbol) is the standard to look for.
If you get a puncture in Snowdonia
Pull over safely — there are passing places on most mountain roads. Turn hazard lights on. If you have a spare, change it carefully on level ground. We cover the whole Snowdonia area and can reach most locations within the national park, though response time on mountain roads is naturally longer than in Bangor or Caernarfon. WhatsApp your location and we’ll come out to you.
Roads to watch
- A4086 (Llanberis Pass) — steep, narrow, severe weather possible year-round at altitude
- A498 (Aberglaslyn Pass) — very tight in places, popular tourist road
- B4391 / Crimea Pass — exposed plateau, first road to ice in winter
- A470 through Dolgellau — longer, faster, but can catch drivers out in rain or mist
This is general guidance to help you decide what to do next — it is not a substitute for a professional inspection. If in doubt, don’t drive on it. Call us and we’ll come to you.