Tyre sizing, ply ratings and load carrying capacity
Agricultural tyres must match tractor axle dimensions and the weight of mounted farm implements.
Core sizing and technical specifications:
- Common rear tyre sizes: Standard 2WD and 4WD tractor rear sizes include 12.4-28 (35 HP segment), 13.6-28 (39 to 45 HP), 14.9-28 (45 to 55 HP), and 16.9-28 (55+ HP).
- Common front tyre sizes: Standard 2WD tractor front steering sizes include 6.00-16, 6.50-16, and 7.50-16; 4WD models feature traction-lug front tyres (e.g. 8.3-20 or 9.5-24).
- Ply Rating (PR): Casing strength typically specified as 6 PR, 8 PR, or 12 PR; higher ply ratings withstand heavy commercial trailer loads and resist stubble punctures.
- Bias-ply vs Radial construction: Bias-ply (cross-ply) offers stiff sidewalls resistant to rocky punctures; radial tyres provide a wider footprint and reduced soil compaction.
Tread lug patterns: Dryland farming vs wetland puddling
Lug design determines traction efficiency across different soil conditions:
Tread lug types and applications:
- R-1 standard agricultural lugs: Chevron-pattern lugs set at 23 or 45-degree angles, providing optimal traction for dryland tillage, sowing, and road haulage.
- R-2 deep-tread lugs: Features double the lug depth of R-1 tyres, designed specifically for wet, sticky paddy fields and sugarcane wetlands.
- Self-cleaning tread: Optimized spacing between lugs allows sticky clay soil to eject naturally as the wheel rotates, preventing mud clogging.
- Center-line wear pads: Extra rubber reinforcement along the tread center provides smooth road haulage and slows highway tread wear.
Pressure maintenance, liquid ballasting and safety
Maintain recommended tyre inflation pressures (12 to 16 PSI for field ploughing, and 20 to 24 PSI for high-speed highway transport) to prevent uneven lug wear. For heavy draft tillage, adding liquid ballasting (filling tubes up to 75% with water) lowers wheel slippage, stabilizes the front axle, and conserves diesel.
Official source
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Bureau of Indian Standards (BIS - Agricultural Tyres) ↗Related on KisanPe
Common questions
What rear tyre size is commonly fitted on 40 to 45 HP tractors?
Tractors in the 40 to 45 HP segment typically use 13.6-28 or 14.9-28 rear drive tyres.
What is the purpose of self-cleaning tread lugs on tractor tyres?
Self-cleaning lugs prevent wet, sticky mud from packing between tread bars, ensuring continuous traction in muddy fields.
Why is correct tyre inflation pressure essential for agricultural tractors?
Proper inflation ensures full tread ground contact, minimizes wheel slippage, saves diesel, and prevents premature tyre wear.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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