The R rating is a slip resistance class from the German ramp test, DIN 51130. It runs from R9, the lowest, to R13, the highest, and tells you how well a floor grips a shoe when the surface is oily.
It is one of several systems. The UK and Australia lean on the pendulum test, and the US uses DCOF. A tile can have results in all three, and they cannot be converted into one another. Ask for the test your market and your customers' regulators recognise.
The DIN 51130 ramp test
A tester wearing standard safety boots walks forwards and backwards on a ramp covered with tiles and coated with oil. The ramp tilts gradually until the tester starts to slip. The average angle sets the class:
- R9: about 6° to 10°.
- R10: about 10° to 19°.
- R11: about 19° to 27°.
- R12: about 27° to 35°.
- R13: above 35°.
Most indoor dry areas need R9 or R10. Wet or greasy areas such as commercial kitchens, ramps and outdoor surfaces need R11 or above. Where each class is used is set out in R11 and R12 slip ratings, and textured outdoor-style tiles in anti-skid tiles.
For barefoot areas such as pool surrounds and showers, a related test, DIN 51097, gives classes A, B and C, with C the most slip resistant.
The pendulum test (PTV)
The pendulum test swings a rubber-shod arm across a wet tile and measures how much it slows. The result is a pendulum test value, or PTV. The method appears in BS 7976 and in EN 16165, and can be used on site as well as in a lab.
UK guidance from the Slip Resistance Group, used by the Health and Safety Executive, treats a wet PTV of 36 or more as low slip potential for level floors. Values of 25 to 35 count as moderate, and below 25 as high. Slopes need higher values. Check the current guidance for your project, as of October 2026.
DCOF in the US
In the US, ANSI A137.1 refers to ANSI A326.3 for measuring the dynamic coefficient of friction, or DCOF, on a wet surface. Tiles for level interior spaces expected to be walked on when wet should have a wet DCOF of 0.42 or more. That figure is a minimum for that use, not a guarantee of safety in every setting.
Why results differ
- The ramp uses oil and boots, the pendulum uses water and rubber, and DCOF uses a sensor sled with a wetting solution.
- A deeply textured tile often scores well on the ramp but may feel rough and hard to clean.
- A smooth matt tile can score modestly on the ramp but acceptably on the pendulum.
- Glossy and polished tiles usually score low on all three when wet.
Finish affects grip strongly, so a rating belongs to one design and finish. See glossy, matt, satin and carving finishes.
What to ask the factory
- A report from an accredited lab, in the method your market uses, for the exact design and finish.
- The date of the test, since surface treatments and glazes change.
- Confirmation that the shipped tiles have the same surface as the tested ones.
- For projects, a lot test or a site test after installation if the specifier requires it.
Next step
Slip resistance is often a legal or contract requirement, not just a selling point. We match the test to your market and have the shipped design tested. Book a free sourcing review to plan it.