goodyear efficientgrip suv tyre test
Building an SUV tyre that offers both grip and low rolling resistance would seem counterintuitive. Andy Enright speaks to Xavier Fraipont from Goodyear to see how it's done.
Just how difficult can designing a tyre be? It turns out that there's more to it than meets the eye. Most of us give only passing consideration to those four palm-sized contact patches that are the only things keeping us from an appointment with the scenery, but there's a huge gulf between the best tyres and the rest that's not always reflected in terms of price.
Goodyear is launching a tyre specially designed for Sports Utility Vehicles (SUVs). Targeted at vehicles such as the Audi Q3 or the Land Rover Evoque, the EfficientGrip SUV tyre needs to be a real decathlete of the tyre world. Whereas a performance road tyre only really has to concentrate on the task of gripping the road and off-road tyres with the job of generating as much traction in mud as possible, a modern SUV is a jack of all trades and needs a tyre that's equally broad in its talents. Therefore it needs to offer decent off-road ability yet ride quietly on road. It needs to offer excellent wet and dry braking grip as well as low rolling resistance for better economy. It sounds an impossible assignment, so I spoke to Xavier Fraipont, Goodyear's Director, Technology Consumer Tyres for a little insight.
Although designed chiefly as a road tyre, the EfficientGrip SUV is also designed for light off-road duties. "It's not as aggressive in its tread design as an off-road tyre like the Wrangler Duratrac, but it retains a high number of biting edges in the tread design. We are homologating the tyre for use as original equipment on the Land Rover Evoque and Land Rover are serious about the off-road performance of all models" Fraipont explains.
"Compared to its predecessor, the Wrangler HP All-Weather, a tyre that was supplied as original equipment on cars like the Land Rover Discovery, Nissan Pathfinder and Volkswagen Amarok, the EfficientGrip SUV offers 10 per cent lower rolling resistance. This translates to a fuel economy benefit of around 2 per cent." It also offers decent winter driving ability, although it's not up to the standard of a proper winter tyre and doesn't carry the snowflake symbol on its sidewalls.
But how can a tyre offer low rolling resistance as well as good grip? The two criteria seem completely opposing. "It's true that the tread compound is the biggest contributor to low rolling resistance, but instead of compromising that, we look at the non- tread elements and work at optimising these so as not to dissipate energy. This means minimising internal stress in the sidewalls, the carcass and the crown of the tyre. We can make significant gains here without affecting grip levels" notes Fraipont.
The figures would seem to bear that out. Goodyear has used a later generation polymer with a high proportion of traction resins and a test conducted by respected German standards organisation T£V demonstrated that against three leading competitors, the EfficientGrip SUV offered a 5 per cent shorter dry braking performance and a 6 per cent shorter wet braking distance. It also excels in offering low noise and excellent durability although an SUV tyre's life will clearly depend on the sort of driving it's subjected to. "Off road performance means a specific requirement for the tread pattern" Fraipont explains. "This has repercussions for noise, for rolling resistance and for mileage." Tests have shown that the EfficientGrip SUV betters its predecessor, the already highly-regarded Wrangler HP all-weather, in each of these criteria.
As far as availability is concerned, the Efficient Grip SUV is manufactured in fifteen sizes, ranging from the 215/55/16 that's fitted to the Audi Q3 to the 235/55/19 rubber that can be fitted to the Land Rover Evoque. At the top of the chart, there's a 255/50/19 size but this marks the upper limit for a tyre of this type. Go much bigger and you're getting into the realm of Ultra High Performance (UHP) vehicles like Porsche Cayennes and BMW X6s which require a different type of rubber again.
Designing a tyre is hugely complex. It's fortunate we have companies like Goodyear to do the thinking for us.