EXPLORE THE NUMBERS
Automotive guides
Understand tire dimensions, fuel economy and ownership costs with practical explanations and worked examples.
Tire essentials
How tire size numbers work
A tire size mixes millimetres, a percentage and inches. Reading those units correctly is the first step to comparing two sizes.
Read the guideTire essentials
What happens when you increase tire width?
Adding width changes more than the number at the start of the size. If the aspect ratio stays the same, diameter grows too.
Read the guideRide & comfort
Does a taller tire improve ride comfort?
A taller overall tire and a taller sidewall are not the same thing. For impact cushioning, the sidewall is the more relevant geometric starting point.
Read the guideTire essentials
How tire size affects speedometer accuracy
A bigger rolling circumference carries the car farther per wheel revolution. Without recalibration, that changes the relationship between indicated speed and road speed.
Read the guideTire essentials
How tire size affects ground clearance
An increase in tire diameter does not lift the vehicle by that full amount. The axle rises by the change in radius.
Read the guideWheel fitment
Can you install wider tires on the same wheel?
The rim diameter must match, but that is only the first check. Wheel width and the exact tire model’s approved rim range decide whether the combination is appropriate.
Read the guideRide & comfort
Tire sidewall height explained
Sidewall height is a percentage of tire width. Equal profile numbers can hide meaningful differences in height.
Read the guideRide & comfort
Large wheels vs small wheels: comfort differences
When overall diameter stays similar, a larger wheel usually requires less tire sidewall. That is the trade-off to examine before changing wheel size.
Read the guideWheel fitment
How wheel offset works
Offset locates the mounting face relative to the wheel centreline. It determines where a wheel sits before tire shape is considered.
Read the guideRunning costs
Tire size and fuel economy
There is no reliable universal fuel-economy percentage for a tire-width change. Several mechanical effects move together.
Read the guideFuel budgeting
How to calculate fuel cost
A useful fuel budget needs three consistent inputs: distance, fuel use and the price per unit of fuel.
Read the guideUnits explained
km/L vs L/100km explained
km/L measures distance per fuel unit. L/100km measures fuel per distance. They describe the same efficiency from opposite directions.
Read the guideUnits explained
US MPG vs UK MPG
A US gallon and an imperial gallon contain different volumes. An MPG figure without a gallon definition is incomplete.
Read the guideHybrid decisions
Petrol vs hybrid running costs
A hybrid’s lower fuel use has to be weighed against its purchase price and the other costs you actually expect to pay.
Read the guideHybrid decisions
How hybrid break-even calculations work
Break-even is the point where cumulative costs meet under a set of assumptions. It is not a promise about future prices or resale.
Read the guideElectric driving
EV charging cost explained
Battery energy use is not always the same as electricity billed at the charger. Charging losses and tariff mix connect the two.
Read the guideElectric driving
EV vs petrol cost comparison
Compare both vehicles over the same distance, ownership period and currency. Cheap energy alone does not establish a lower total cost.
Read the guideOwnership costs
How much does driving really cost per km?
Cost per kilometre can mean fuel alone, marginal trip cost or total ownership cost. Specify the boundary before comparing numbers.
Read the guideOwnership costs
How vehicle depreciation affects ownership cost
The price paid for a car is not necessarily its final ownership cost. Resale value determines how much of that purchase price is retained.
Read the guideOwnership costs
How to compare the true cost of two cars
A fair comparison holds the ownership period, distance and accounting boundaries constant for both vehicles.
Read the guide