Tyre Size Guide
Everything you need to find the right tyre or rim, from reading the size on your sidewall to checking load and speed ratings. For delivery, returns and other common questions, see our FAQs.
Download the size guide (PDF)How to Read a Trailer or Caravan Tyre Size
Your tyre size is printed on the sidewall of your current tyre. On trailer and caravan tyres it will look something like the example below. Always match this exactly when ordering a replacement.
The width of the tyre in millimetres.
The height of the sidewall as a percentage of the width.
R means the tyre has a radial construction.
The diameter of the rim the tyre fits, in inches.
A reinforced tyre built to carry heavier loads.
The maximum load per tyre. 86 means 530kg. See the load ratings table.
The maximum speed. N means 87mph. See the speed ratings table.
Some tyres show two load index numbers, for example 185/70R13C 106/104N. The first number applies when the tyre is fitted as a single wheel, and the second when fitted as a twin.
Shop caravan and trailer tyres or trailer wheel and tyre assemblies.
How to Read a Quad, ATV or Turf Tyre Size
Quad, ATV and turf tyres use a different format to trailer tyres. The size is shown as three numbers, for example 25x8.00-12.
The overall height of the tyre in inches.
The section width of the tyre in inches.
The diameter of the rim the tyre fits, in inches.
We do not recommend changing from the manufacturer's specified size, as this takes into account the load, speed and gearing of the vehicle.
Shop quad and ATV tyres or turf tyres.
How to Measure a Trailer Rim
To find the right trailer rim, you will need to know:
- Rim width and diameter, in inches.
- Stud count, the number of wheel studs, usually 4 or 5.
- PCD (pitch circle diameter), an imaginary circle formed through the centre of the rim's stud holes. Common trailer PCDs include 4 inch, 100mm, 112mm, 115mm, 5.5 inch and 6.5 inch.
- Centre bore, the diameter of the hole in the centre of the rim.
- Offset (ET), how far the mounting face sits from the centre line of the rim.
What's stamped on the rim?
Rim width, diameter and offset are often stamped onto the rim, and will look something like 5.5Jx12 ET0. In this example, 5.5 is the rim width in inches, 12 is the diameter in inches and ET0 is the offset. PCD and centre bore generally need to be measured.
Measuring PCD
Measurement practices vary depending on the number of studs.
Measuring centre bore
Some PCD sizes are very close together. A 4 inch PCD (101.6mm) and a 100mm PCD are less than 2mm apart, which is hard to tell by eye. Measuring the centre bore as well will confirm which one you have.
| PCD | Centre bore |
|---|---|
| 4 inch | 67mm |
| 100mm | 60mm |
If your PCD measures around 100mm, check the centre bore. A 67mm centre bore means you have a 4 inch PCD, and a 60mm centre bore means you have a 100mm PCD.
Shop trailer rims.
Tyre Speed Ratings
The speed rating is the letter at the end of the tyre size. It shows the maximum speed the tyre is designed for.
| Speed symbol | Speed mph |
|---|---|
| L | 75 |
| M | 81 |
| N | 87 |
| P | 93 |
| Q | 99 |
| R | 106 |
| S | 112 |
| T | 118 |
| U | 124 |
| H | 130 |
| V | 149 |
| W | 169 |
| Y | 186 |
| (Y) | 186+ |
Tyre Load Ratings
The load index is the number before the speed rating. It shows the maximum load each tyre can carry.
| Load index | Load in kg |
|---|---|
| 62 | 265 |
| 63 | 272 |
| 64 | 280 |
| 65 | 290 |
| 66 | 300 |
| 67 | 307 |
| 68 | 315 |
| 69 | 325 |
| 70 | 335 |
| 71 | 345 |
| 72 | 355 |
| 73 | 365 |
| 74 | 375 |
| 75 | 387 |
| 76 | 400 |
| 77 | 412 |
| 78 | 425 |
| 79 | 437 |
| 80 | 450 |
| 81 | 462 |
| 82 | 475 |
| 83 | 487 |
| Load index | Load in kg |
|---|---|
| 84 | 500 |
| 85 | 515 |
| 86 | 530 |
| 87 | 545 |
| 88 | 560 |
| 89 | 580 |
| 90 | 600 |
| 91 | 615 |
| 92 | 630 |
| 93 | 650 |
| 94 | 670 |
| 95 | 690 |
| 96 | 710 |
| 97 | 730 |
| 98 | 750 |
| 99 | 775 |
| 100 | 800 |
| 101 | 825 |
| 102 | 850 |
| 103 | 875 |
| 104 | 900 |
| 105 | 925 |
| Load index | Load in kg |
|---|---|
| 106 | 950 |
| 107 | 975 |
| 108 | 1000 |
| 109 | 1030 |
| 110 | 1060 |
| 111 | 1090 |
| 112 | 1120 |
| 113 | 1150 |
| 114 | 1180 |
| 115 | 1215 |
| 116 | 1250 |
| 117 | 1285 |
| 118 | 1320 |
| 119 | 1360 |
| 120 | 1400 |
| 121 | 1450 |
| 122 | 1500 |
| 123 | 1550 |
| 124 | 1600 |
| 125 | 1650 |
| 126 | 1700 |
Still have questions?
Our FAQs cover delivery, returns and choosing the right tyre, wheel or rim. If you can't find your answer there, get in touch and our team will help.