The Tyre Desk
Practical tyre guides, calculators and reference tables for dealers, fitters and fleet teams. Free to use, with no login required.
Find practical guidance on tyre markings, load ratings, size changes and casing care. The Tyre Desk brings the key reference material together to support everyday specification and fitting decisions.
Created for tyre dealers, fitters, workshop managers and fleet teams, these resources are free to use and require no account.
Technical support when you need it. If you need help applying the information to a particular vehicle or machine, our team can help you identify the next steps.
Each calculator explains its method and limitations. Always use the tyre and vehicle manufacturer’s current data when confirming a fitment or operating pressure.
Guides
Ten practical guides to tyre specification across commercial, agricultural and off-highway applications.
How to read a truck tyre sidewall
Every marking on a commercial sidewall in the order you meet them, from the size through the DOT code to the regroovable mark.
Read more →Load index and speed symbol
What the service description means, why some tyres carry two load indices, and how the load and speed limits interact.
Read more →Ply rating and load range
Understand ply rating, load range letters and how these strength ratings are used.
Read more →IF and VF agricultural tyres
High-flexion constructions: more load at the same pressure or the same load at lower pressure, and how to choose the right construction for the job.
Read more →Agricultural tyre pressure
Working from load and pressure tables, field against road pressures, and what a single compromise pressure costs in yield and tyre life.
Read more →OTR tyre codes and star ratings
Understand TRA codes, E, L and G service families, star ratings and TKPH for earthmover applications.
Read more →Foam filling explained
What the process involves, where a filled pneumatic beats a solid, what it does to machine weight, and what it costs at end of life.
Read more →Forklift tyres: cushion, solid or pneumatic
The three constructions compared on load, ride, floor surface and cost, including non-marking compounds.
Read more →Retread or replace
How to judge a casing, what makes one worth a second life, and when a retread beats a new budget tyre on cost per kilometre.
Read more →Rolling circumference
Loaded against free circumference, what a size change does to gearing, tachographs and front-to-rear lead on a four-wheel-drive tractor.
Read more →Calculators
Six tools to help decode markings, compare sizes and assess costs. Each includes guidance on using the results and explains any estimates.
Sidewall decoder
Paste any commercial size and get width, aspect, construction, diameter, load index in kilograms and speed symbol in km/h.
Open the decoder →Exact lookupLoad index lookup
Any index from 50 to 200 converted to kilograms per tyre, and totalled across a set. Read straight from the ISO table.
Open the lookup →Exact lookupAxle load to load index
Enter an axle weight, the tyres carrying it and a safety margin, and get the minimum load index with the headroom it leaves.
Open the calculator →EstimateRolling circumference & speedometer error
Diameter, circumference and revolutions per kilometre, plus the percentage difference and speedometer error between two sizes.
Open the calculator →EstimateFoam fill — weight and cost
Estimated fill volume, added weight and material cost for a size, built from nominal dimensions rather than a cavity table.
Open the estimator →Your figuresCost per kilometre
Compare two tyres on cost per kilometre instead of purchase price, and scale the difference across a fleet.
Open the calculator →Reference tables
Quick reference tables for load index, speed symbols, and load range and ply rating.
Load index, 100 to 199. The ISO load index converted to kilograms and pounds per tyre, covering light van through to heavy earthmover. Remember that the figure is the maximum load at the tyre’s marked inflation pressure — an under-inflated tyre does not carry its index.
Speed symbols. From the A-series used on slow-moving industrial and agricultural equipment through to the road-going letters, in km/h and mph. Note that the sequence is not alphabetical at the top end: H sits between U and V.
Load range and ply rating. The older casing-strength system, still standard on agricultural, industrial and trailer sizes. The letters and the ply ratings are equivalent to each other, but neither converts directly to a load index, because the load a given casing strength supports depends on the size of the tyre.
Elsewhere on the site
Downloads provides links to online resources and explains how to request product documentation, load charts and safety information.
News covers what changes in the business: new distributorships, services and range additions. Who we supply names the kinds of business that buy from us.
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