How tyre tread patterns affect braking – Bendix explains

Along with suspension set up, the type of tyre fitted to a vehicle and its tread pattern, is another major contributor to consistent braking performance.

In four-wheel drives, suspension and tyre ‘upgrades’ are two of the most common modifications, and often the first ones applied by owners starting down the path to modification.

When suspension is too soft, excessive body movement during braking can unsettle the vehicle, causing uneven weight distribution and potentially compromising traction. Suspension that’s too stiff can reduce the tyre contact on the road which will increase braking distance. Taller suspension can also affect braking, because centre of gravity is now higher.

Tyre swaps beyond OEM specification and changing tyre bias will also have an impact, as was demonstrated through local testing last year by a leading tyre manufacturer.

The difference in braking performance between road biased, all-terrain and mud-terrain tyres is considerable, with mud terrains typically taking up to five metres longer to stop from 70 kph than equivalent road biased counterparts.

Using VBOX diagnostic equipment on a closed circuit, the company placed a variety of its road, all terrain and mud tyres under scrutiny along with those of several competitors. Using 265/65R17 size tyres – the most common dimensions fitted to vehicles sold in Australia – braking was undertaken on the skid pan, from 70 kilometres per hour to standstill in both wet and dry conditions.

On all occasions, stopping distance between the road tyres and mud terrains differed by approximately five metres (a typical car length), with all terrain variants falling between. While some of the reduced on-road braking was attributed to mud terrain tyres having harder, chunkier tread with extra space between the lugs (less contact patch with the road) to allow them to self-clean, mud terrain tyres, even when the same dimensions, are typically heavier.

The extra weight which is upwards of two kilograms can be attributed to thicker sidewall construction and harder tread, and this adds to the rotational mass of the tyre. And although marked as 265/65R17, mud terrain tyres can at times be taller than what’s stated.

Rotational mass refers to any components that rotate with the wheel assembly: tyres, wheels and lug nuts etc. The further away the mass is from the axis of rotation, and the heavier the weight of the mass, the larger the rotational mass becomes, and the greater the force that’s needed to stop the assembly from rotating.

Mud-terrain tyres have a reduced contact patch with the road and are generally heavier and taller (even at the same listed size), contributing to a greater rotational mass.

Neutralising the impact of rotational mass
The ideal situation for owners of four-wheel drives is to have a second set of wheels and tyres for when they use their vehicles in demanding terrain, but of course, this is expensive. A compromise could be to select all terrains and forgo some braking performance in exchange for additional ability off the bitumen.

Another option is to consider brake upgrades – these can be applied in different stages depending on owners’ requirements and budget.

Better friction material
The easiest and most cost-effective starting point is to replace OE brake pads and shoes (in the case of rear drum brakes) with alternatives such as Bendix’s Ultimate 4WD™ Brake Pads and Brake Shoes, which feature friction material that’s optimised for demanding off-road use and provide improved high temperature stability.

Braided brake lines
Another easy upgrade is fitting braided brake lines. Bendix Ultimate 4WD™ Brake Hoses, feature PTFE (Teflon®) tubing that’s wrapped in woven stainless steel 304 braid. This tough construction means they won’t expand under high pressure, ensuring a firm and responsive pedal feel.

Rotor and drum upgrades
With a bit more investment, owners can upgrade their disc rotors and / or drums. Bendix’s Ultimate 4WD™ Brake Drum Upgrade Kit features High Carbon Metallurgy, SwiftFit protective zinc coating and Epoxy Coated Hub, leading to improved braking. The Ultimate 4WD™ Disc Brake Rotors feature four-wheel-drive specific metallurgy that increases rotor strength at elevated temperatures while also providing high wear resistance. Other benefits include high efficiency cooling pillars that channel cool air into the rotor. Additional performance is achieved through Bendix’s Diamond Tip Slot technology which helps to expel gasses, dirt and water more efficiently from the rotor surface.

A range of brake upgrades are available from Bendix to improve the braking performance of vehicles that have been optioned with aggressive mud-terrain tyres. 

Complete brake kits
For added convenience and cost effectiveness, complete brake packages such as Bendix’s Ultimate 4WD™ Brake Upgrade Kits, offer everything needed for a significant brake boost (brake pads, rotors, brake hoses, brake fluid, Ceramasil lubricant, rotor wipes and more) in a single box. And for the very best performance boost, Bendix also offer its Ultimate 4WD™ Big Brake Upgrade Kits – these are premium packages with larger diamond tip slot front rotors, powerful 6-piston front calipers (front kit), a rear drum to disc conversion and all the associated parts required to complete the work (rear kit), along with Ultimate 4WD™ Brake Pads, Brake Hoses and the ancillary products mentioned in the standard Ultimate 4WD™ Brake Upgrade Kit.