VF Vs IF: What They Are And Why They Matter
IF (Improved Flexion) and VF (Very High Flexion) tyres carry more load at the same pressure, or the same load at lower pressure. As a rule of thumb: IF ≈ +20% load at the same pressure; VF ≈ +40%. That extra flex builds a longer, wider footprint without overstressing the carcass.
Compared with standard radials, IF/VF deliver less compaction, better traction, lower fuel use, and a smoother road ride. They suit tractors, self-propelled sprayers, and flotation trailers. Manufacturer load/speed tables from brands like Michelin, BKT and ATG are essential to set them correctly. For machine-specific advice, see our tractor tyres range and read the ultimate guide to tractor tyres for background.
Why Correct Setup Extends Tyre Life And Protects Soil
Tyre life is governed by the heat–load–speed triangle. Too much load at too little pressure, or too much speed for the pressure, builds heat. Heat fatigues cords, weakens the bead, and accelerates wear.
Overinflation for field work shrinks the footprint and causes centre wear and shoulder scrub on turns. Underinflation on the road increases flex and heat, risking sidewall damage. Get pressure right and you reduce compaction, improve traction and steering, and stay safe at speed. For a deeper dive into the costs, see the cost of poor tyre care.
Step 1: Measure True Axle Loads (With Implements Fitted)
Use a farm weighbridge or portable axle scales. Measure empty and fully laden. Fit the front loader or linkage tools. Add front ballast. Hitch trailers at transport height to capture drawbar transfer. For sprayers, weigh with a full tank and a half tank.
Record front and rear axles separately. Note your maximum transport speed and the typical road distance per day, as these govern heat risk. If you run trailers, understand how hitch position and suspension move weight; our guide to choosing the right trailer axle and wheels explains the basics.
- Front axle: ____ kg
- Rear axle: ____ kg
- Total weight: ____ kg
- Max transport speed: ____ kph
- Duty split: ____% field / ____% road
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Step 2: Choose The Right VF/IF Sizes And Wheels
Select tyre size and construction from manufacturer tables using your measured axle loads and speeds. Match load index and speed symbol to your duty. Keep rolling circumference within maker tolerances to maintain gearing and MFWD lead/lag.
Wheels matter as much as tyres. Pair section width to the recommended rim width, and choose diameter, offset and track to maintain clearance and row spacing. Fieldens OTR Ltd builds bespoke wheels for exact track settings, duals or conversions, with ISO 9001-backed quality and precision fitting. Explore our agricultural wheels for specification options.
Step 3: Set Safe Field And Road Pressures
Use the tyre maker’s load/speed tables (Michelin, BKT, ATG). 1) Take the heaviest axle load for each job. 2) Look up the pressure needed to carry that load at your target speed. 3) Set field pressure to the lowest value that safely supports the load at field speeds. 4) Set a higher road pressure for transport speed and distance. Respect minimum inflation limits and use a calibrated gauge.
Worked example: Rear axle load 8,000 kg at 10 kph needs 0.8 bar (field). For 40 kph road work the table shows 1.4 bar. Either operate a two-pressure policy or use CTIS if fitted. See why speed and duty change heat build-up in demanding conditions for rim and tire.
Step 4: Validate Setup And Prevent Heat And Shoulder Wear
In the field, the footprint should be long and even. Lugs should contact across the full tread. Sidewalls should flex in a controlled way without folding. If the shoulders polish while the centre stays dull, pressure is too high for that load.
After a 10–20 km road run at transport speed, check sidewall and tread with an IR thermometer. If temperatures are abnormally high, raise pressure or reduce speed/load. Re-check settings when the season or implement changes.
Application-Specific Tuning: Tractors, Sprayers And Trailers
Sprayers combine high speeds with fast-changing tank weights. VF rowcrop tyres with the correct speed symbol help maintain footprint at lower pressures; re-check pressures between full and half tanks. On trailed sprayers, consider wider VF rears for headland protection.
Grain and slurry trailers benefit from high-capacity flotation tyres set for gross load and speed; verify even load share across axles to prevent overloading a single axle. On mixed ag/industrial work, prioritise carcass durability and puncture resistance. Fieldens OTR Ltd can specify robust constructions and Fieldens Polycoat Tyrefill where punctures are frequent.
This image was generated with AI and may not always represent the product or service exactly.
Avoid These Common Mistakes
Do not guess pressures or copy a neighbour’s setup. Never mix standard, IF and VF on the same axle. Do not run field pressures on the road. Always respect speed symbols at the pressures you use.
Match tyre to rim width to avoid shoulder wear. Specify offset and track to maintain clearance. After fitting, torque wheel fixings to spec and re-torque after the first day’s work. Keep a simple record of pressures by implement and season to avoid errors.
Maintenance That Protects Service Life
Check pressures weekly with a calibrated gauge. Inspect tread and sidewalls for cuts, stubble damage and bulges. Confirm alignment and MFWD lead/lag are within tolerance. Fix slow leaks early.
Reset pressures with seasonal temperature changes or duty changes. Rotate tyres if wear is uneven. Store machines out of sunlight or block them up to take weight off tyres. Retread only when the carcass is sound; VF/IF casings must be in good condition to justify retread.
How Fieldens OTR Configures VF/IF Packages That Work
Fieldens OTR Ltd provides end-to-end support: on-farm axle load measurement, tyre selection to duty, bespoke wheel manufacturing for exact track and offset, and precision fitting under ISO 9001 quality. We work with leading brands including Michelin, BKT and ATG.
We support agricultural, construction and industrial fleets nationwide, and can specify Fieldens Polycoat Tyrefill for puncture-prone work. For more insight and updates, visit our blog.
FAQs
Can I Run VF Tyres At The Same Pressure As Standard Radials?
Yes, but you lose the benefit. VF allows the same load at lower pressure or more load at the same pressure. Use the tables to set the lowest safe pressure for the job.
Do I Need Different Pressures For Field And Road?
Often yes. Field work prefers lower pressure for footprint; road work needs higher pressure for speed and heat control. A two-pressure policy or CTIS helps.
How Do I Know If I’m Overinflated In The Field?
Look for a short, narrow footprint and polished shoulders with dull centre lugs. Reduce pressure within the maker’s limits until the footprint lengthens evenly.
Will VF/IF Tyres Fit My Existing Rims?
Sometimes. Check recommended rim width and diameter for the tyre size. If the rim is wrong, specify the correct wheel with the right offset and track.
What Temperatures Are A Warning Sign After Road Work?
If sidewall or tread temperatures feel excessively hot or climb rapidly run to run, increase pressure or reduce speed/load. Use an IR thermometer for consistency.
Do Sprayers Need VF Rowcrops?
They benefit from VF rowcrops because of high speed and variable tank weight. Set pressures for full-tank weight and recheck at half tank to control heat.