Decipher it: 4×4 tyre sidewall text explained Posted on 22 March 2012 Do you speak tyre? Those numbers and letters on the sidewall of your 4×4 tyre aren’t alphabet soup. To the untrained eye a tyre has a lot of random characters peppered all over it. Knowing what they mean will empower you to make better, safer choices when replacing or upgrading your 4×4’s tyres. THE DIFFERENT TYPES OF 4X4 TYRES 4×4 tyres can be divided in four categories, depending on the intended ratio of on- versus off-road usage. The two-letter designation usually follows the brand or range name – Bridgestone/Dueler in this case HP: High-performance road tyres (95 per cent on-road) HT: Highway-terrain (80/20) AT: All-terrain 4×4 (50/50) MT: Mud-terrain 4×4 (90/10) Here’s more information and images of these 4×4 tyre types TYRE INDEX MARKINGS The text sequence above indicates size, build type and load and speed tolerance. This tyre doesn’t have it but, some manufacturers’ size designations are preceded by a letter indicating the vehicle type the tyre is designed for. P for ‘passenger’ and LT for ‘light truck’ are most common. SIZING UP We’ll use the 265/65R17 112S as an example: * 265 is the tread width in millimeters. A wider tyre has a negative impact on fuel efficiency, but improves traction. * 65 is the tyre profile and, expressed as a percentage, represents the relationship between sidewall height and tread width. In this example, sidewall height is 65 per cent of the 265-mm width. TIP TO REMEMBER: Taller sidewalls improve a vehicle’s undercarriage clearance. But if you’re increasing width and/or profile, check the new tyres don’t rub on bodywork and suspension bits during turning and axle articulation. * R tells us it’s a radial tyre, which contains multiple steel cords and provides more strength, stability and puncture resistance than older technology bias-ply designs. * 17 indicates the rim diameter in inches. * 112S, usually the last number and letter combination in the sequence, represents the load index (112) and speed rating (S). LOAD INDEX NUMBER Load index number (112) indicates the weight a tyre is approved to carry at maximum inflation. You’ll need a full chart to determine the weight capacity of all tyres, but the table below should cover the tyres most overlanders would use: SPEED RATING The letter indicating the speed rating, S in this case, represents the maximum speed at which the tyre can carry a load corresponding to its load index. NOTE: It’s important to comply with vehicle manufacturers’ load index and speed rating specs regardless of your actual speed, not only for safety’s sake but non-compliance makes insurance companies blind and deaf. ROUND IT UP To sum up, a 265/65R17 112S tyre has a tread width of 265 millimetres, a profile of 65 and is a radial tyre that fits on a 17-inch rim. The load index (112) indicates a maximum load capacity of 1120kg and a S speed rating certifies it up to 180kph. And then there’s this… How to decipher the American Off-road Tyre Marking System Most off-road tyres use the indexing format I’ve outlined above, but some use an older American marking system, for example 31×10.5R 15 LT. 31 = The outside diameter of the tyre in inches 10.5 = The section/tread width of the tyre in inches R = Radial Construction 15 = Rim diameter in inches LT = Light truck Related Posts Nifty gadgets to pack for your Christmas holiday (or to gift!) 8 December 2022 This Christmas season just got a whole lot better with these helpful tech gadgets, that... read more New concept store for you and your furry companions opens in Cape Town 28 November 2022 When history and modernity combine with panache, you get extraordinary. This can very much be... read more Aloha! Maui Jim’s latest sunglass range hits South African shores 22 November 2022 Summer in South Africa has a few things in common with summer in Maui in... read more PREV ARTICLE NEXT ARTICLE
Nifty gadgets to pack for your Christmas holiday (or to gift!) 8 December 2022 This Christmas season just got a whole lot better with these helpful tech gadgets, that... read more
New concept store for you and your furry companions opens in Cape Town 28 November 2022 When history and modernity combine with panache, you get extraordinary. This can very much be... read more
Aloha! Maui Jim’s latest sunglass range hits South African shores 22 November 2022 Summer in South Africa has a few things in common with summer in Maui in... read more