Tyre Size Fuel Consumption Calculator

Tyre Size Fuel Efficiency Guide

Calculate how tyre size and efficiency ratings affect your vehicle’s fuel consumption and estimate potential savings.

How It Works

The calculator estimates fuel consumption based on tyre size (width, aspect ratio, rim diameter) and EU fuel efficiency ratings, factoring in annual mileage, fuel price, and vehicle MPG. It compares current and new tyre specifications to calculate annual fuel costs and savings.

Litres/Mile = 4.54609 / MPG

Annual Litres = Mileage × Litres/Mile × Efficiency Factor × Size Factor

Annual Cost = Annual Litres × Fuel Price (£/litre)

Savings = Current Cost - New Cost

Tyre Specifications

Tyre size (e.g., 205/55R16) consists of:

• Width (mm): Wider tyres increase rolling resistance, impacting fuel efficiency.
• Aspect Ratio (%): Lower ratios (e.g., 50%) create stiffer sidewalls, affecting efficiency and comfort.
• Rim Diameter (inches): Larger rims increase rotational mass, potentially reducing efficiency.

EU Tyre Label Efficiency Ratings

EU ratings range from A (most efficient) to G (least efficient), with approximate fuel consumption impacts:

Rating	Fuel Efficiency Impact
A	Baseline (Most Efficient)
B	+2.5% consumption vs A
C	+5% consumption vs A
E	+7.5% consumption vs A
F	+10% consumption vs A
G	+15% consumption vs A

Key Factors Affecting Fuel Consumption

• Tyre Size: Larger diameters (e.g., 215/50R17 vs 205/55R16) increase fuel use by ~1% per 1% diameter increase.
• Efficiency Rating: Higher ratings (A/B) reduce fuel consumption compared to lower ratings (F/G).
• Mileage: Higher annual mileage amplifies the impact of tyre efficiency.
• Fuel Price: Higher prices increase the financial impact of efficiency changes.
• MPG: Lower MPG vehicles consume more fuel, making tyre efficiency more significant.

Tips for Optimizing Fuel Efficiency

• Choose manufacturer-recommended tyre sizes to balance efficiency and performance.
• Select tyres with A or B efficiency ratings for maximum savings.
• Maintain proper tyre pressure (check monthly) to reduce rolling resistance.
• Opt for lightweight wheels to minimize rotational mass.
• Balance efficiency with safety and handling needs for your vehicle.

Example Calculation

For a vehicle with 205/55R16 (C-rated) tyres, 10,000 miles/year, £1.30/litre fuel, 50 MPG, upgrading to 215/50R16 (A-rated) tyres:

Current Diameter = 16 + 2 × (205 × 0.55 / 25.4) = 24.45 inches

New Diameter = 16 + 2 × (215 × 0.50 / 25.4) = 24.46 inches (Size Factor = 24.46 / 24.45 ≈ 1.0004)

Litres/Mile = 4.54609 / 50 = 0.0909

Current Annual Litres = 10,000 × 0.0909 × 1.05 = 954.39

New Annual Litres = 10,000 × 0.0909 × 1.00 × 1.0004 = 909.27

Current Cost = 954.39 × 1.30 = £1,240.71

New Cost = 909.27 × 1.30 = £1,182.05

Savings = £1,240.71 - £1,182.05 = £58.66 (4.7%)

Final Considerations

Optimizing tyre size and efficiency ratings can lead to significant fuel savings, especially for high-mileage drivers. Always verify tyre compatibility with your vehicle and consider odometer accuracy when changing sizes.