Increasing the width of your wheels and tyres can have some potential benefits but also drawbacks, the same applies with increasing track width, usually by installing spacers.
In this article, I'll explain the benefits and drawbacks of both.
Benefits of Wider Wheels
Wider wheels can provide several benefits, such as the following.
The contact patch between the tyre and the road is bigger with wider tyres. Increased tyre-to-road surface area improves grip and traction.
Enhanced cornering speed, quicker launches and acceleration, and faster track times are all possible thanks to increased grip.
The importance of high-speed stability cannot be overstated, and wider wheels and tyres may help.
Due to decreased body-roll and weight transfer, wider wheels improves stability.
This implies that when a vehicle performs a high-speed manoeuvre like swerving or speeding over bumps on the road, it is less likely to become unstable.
Reduced body-roll is a benefit of greater track width owing to bigger tyres and wheels. As previously stated, less body-roll enhances high-speed stability.
Minimising body-roll provides various advantages, such as enhancing steering responsiveness, cornering speed, and lowering weight transfer.
Drawbacks of Wider Wheels
There are also many drawbacks to wider wheels.
Tyres take longer to heat up
More likely to tramline
Extra unsprung weight
Reduced steering sensitivity
Modification may be needed
Increasing the width of the wheels and tyres can increase the surface area, increasing both air resistance and friction, causing more drag.
This can reduce top speed, efficiency, and even acceleration (when grip isn't a factor).
As mentioned, increased drag can result in reduced efficiency. This means your car will use more fuel, reducing its MPG.
Tyres Take Longer to Heat Up
Increasing the width of the tyre can cause it to take longer to heat up, reducing grip from a cold start.
More Likely to Tramline
Tramlining is what happens when the vehicle tends to follow imperfections in the road, such as grooves and ridges.
It is more likely to occur with wider tyres and wheels, it's commonly noticed in sports cars.
Extra Unsprung Weight
Increasing unsprung weight can have a significant impact on your vehicles handling and performance, especially since the wheels and tyres are also rotating mass, as they're directly connected to the drivetrain.
Wider wheels and tyres could result in reduced tracking over bumps and reduce acceleration due to the increased weight.
Reduced Steering Sensitivity
Increasing width of the wheels can result in a reduced steering sensitivity, this may be disadvantageous in track days or situations which require quick steering inputs.
Wider tyres of course mean more expensive tyres, this is an obvious drawback.
Modification May Be Needed
Bodywork, chassis, or suspension modification may be needed for the install of wider wheels and tyres.
This can include rolling or cutting the arches, installing wide arch kits, adjustable coilovers, etc.
Benefits of a Wider Track Width
A wider track width can have similar benefits to increasing wheel and tyre width.
Lessened effective spring rate
As is the case with wider wheels and tyres, a wider track width can also result in improved stability, especially at high speeds.
Reduced body-roll as a result of wider track width can enhance handling, especially during cornering.
Lessened Effective Spring Rate
Due to a change in suspension geometry, the effective spring rate will be lowered. To put it another way, the wheel has greater leverage on the springs/shocks.
It implies that for a certain amount of vertical wheel movement, there will be less spring movement.
This effect of a wider track width can enhance grip.
Drawbacks of a Wider Track Width
A wider track width has several disadvantages, which are outlined below.
Increased tuning circle
Increased Turning Circle
A greater turning circle will come from a wider track width, making tighter bends more difficult and the vehicle less nimble.
It also reduces the sensitivity of steering inputs.
As previously stated, higher track width increases the vehicle's surface area, increasing drag and, as a consequence, lowering peak speed and acceleration.
This extra drag also results in reduced efficiency, reducing MPG and increasing fuel cost.
Wider Wheels vs Wider Track-Width
People often want to install wide-body kits and have a larger track width, but they don't want to put bigger wheels and tyres on their vehicles. This is one reason why wheel spacers are most commonly used.
Wheel spacers allow you to increase the car's track width without increasing the tyre or wheel diameter, most people do it for the aesthetics, though. Although installing wheel spacers is the less expensive and a simpler solution, it is not without it's flaws.
Certain suspension and drivetrain components, including as driveshafts, struts, and wheel bearings, may be subjected to higher stress.
Small wheel spacers, such as those about 5mm in diameter, may help increase brake clearance, help to tune a car's track width, and fill in an arch gap.
However, large wheel spacers, such as those of around 15mm and higher, may put additional pressure on components and have the same downsides as larger wheels without the benefits.
Therefore, it fully depends on the use-case of your vehicle. If you want a highly stable car for high speed, installing larger wheel spacers and wider wheels may be a good idea. If you want a nimble car for track use, smaller spacers and standard width wheels are ideal.