By William Schertz, ERJ staff (TB)
Akron, Ohio-At what point does â€œlow profileâ€ become â€œstandard?â€
That's the question the tyre industry is asking itself as low-profile passenger tyres continue to gain a larger share in the consumer OE business and the aftermarket.
According to Tire & Rim Association data, the number of auto rim diameters and tyre aspect ratios recognised by the organisation has increased to 328 from 213 since 2000. About 86 percent of these new sizes have rim diameters of 18 inches or larger and aspect ratios of 55 percent or lower. Nearly half of all recognised aspect ratios are 50 percent or lower.
â€œPerformance tyres aren't just for sports cars anymore,â€ said Bob Toth, Goodyear's director of products and innovation for North America, during a panel discussion at the 2010 ITEC Show in Cleveland. â€œPerformance tyres are coming on a wide variety of cars, and it's because the OEMs are using the tyre as an integral part of the suspension to fine tune it to optimise stopping and handling.
â€œâ€¦You could say that high-performance tyres were born in racing and they transgressed over to niche market street products, but the reality is they're becoming appreciably the norm in the market place.â€
Mark Chung, Yokohama Tire Corp.'s director, corporate strategy and planning, concurred, noting even economy cars are coming equipped with lower-profile sizes.
â€œThis trend will continue as we are now seeing everyday vehicles, such as the (Toyota) Camry or (Chevrolet) Malibu, ship from the factory with larger wheel diameters versus the previous generations,â€ he told Tire Business recently. â€œIf auto shows provide any accurate forward-looking indications, it appears this trend will continue. The opportunity for tyre manufacturers and dealers alike is to develop and sell tyres that are compatible with vehicles with lower-profile tyres.â€
The trend is being driven primarily by auto makers, said Matt Edmonds, vice president of South Bend, Ind.-based Internet/mail order retailer Tire Rack, as they aim to provide customers with all-around sportier vehicles and better handling.
'The tyre manufacturers have gone a long way in developing tyres to maintain ride quality as they've reduced the sidewall of the tyre, and at the same time they've had to strengthen the sidewall of the tyresâ€¦. All of that at the same time the OEMs are squeezing them to get everything they can out of the tyre from a rolling-resistance standpoint to improve the CAFE (corporate average fuel economy) numbers,â€ he said.
Edmonds added that while most people associate low-profile tyres with performance tyres, that is no longer an accurate assumption.
â€œPeople are looking at the aspect ratio of the tyre and saying, 'Well, gosh, it's a low-profile tyre, so it's gotta be a performance tyre.' That's not necessarily true anymore,â€ he said. â€œYou have a lot of vehicles that have a 50-, 55-, 60-aspect ratio tyre that has an all-season grand touring tyre on it, not necessarily a performance tyre.
â€œâ€¦The fact that you have a lot of vehicles-SUVs and light trucks-coming with what people are perceiving as low-profile tyres, it's being driven by the packaging by the OEMs wanting the appearance of a big wheel on the vehicle but also going to a larger wheel.
â€œAs that wheel gets bigger, it gives them more room behind that wheel to work-to put brakes, to put suspension components, to have clearance to have those kinds of things happen behind the wheel.â€
Edmonds said that tyres in general have increased in overall size in the last 15 years and even low-profile tyres aren't as â€œlowâ€ as they once were.
â€œWe've seen aspect ratios change, migrate away from the 70- and 75-series tyres which were so popular in the '70s and '90s, to tyres that are 60, 55 and even 50 (series),â€ Edmonds said. â€œThe other difference is the outside diameters of the tyres have changes and the width of the tyres, so consequently with the aspect ratio being a percentage of the tyre width, low profile maybe isn't quite as low as it used to be.â€
For better or worse
While the proliferation of low-profile tyre models and sizes has led to the availability of some stylish designs, there are some downsides.
The problems start with dealers, as the sidewall stiffness makes dismounting and mounting a more difficult task than larger tyre sizes.
â€œThe biggest problem with low-profile (tyres) is you usually have to pay extra to get them mounted,â€ said Darold Schaefer, owner of R&R Tire Shop in Mankato, Minn. â€œâ€¦Outside of bigger towns, you're not even going to get people to mount them half the time.â€
Schaefer said he believes the allure of low-profile tyres is â€œ90-percent appearanceâ€ and that they have no major benefits outside of improved steering response and looking â€œcool.â€
â€œThe lower the profile tyre, the worse the ride you're going to get and the more often you're going to bend the wheel,â€ he said. â€œIt's harder on your shocks, it's harder on everything, so what's the advantage?â€
Low-profile tyres, along with the rims they're mounted on, are especially susceptible to damage from various road hazards because there's less air to provide cushion from bumps.
â€œThat tyre is the first line of defense for your vehicle with potholes,â€ Edmonds said. â€œOne of the things people don't think about is that sidewall is the first piece of a suspension on your vehicle that absorbs bumps in the road, that absorbs a pothole, so it is an important part of your vehicle suspension. It emphasises the need to maintain your tyres and keep your air pressure properly set.â€
Edmonds said when people contact Tire Rack looking to do plus-one and plus-two fitments on their vehicles, â€œif they live in an area where there are a lot of potholes and it's a vehicle they're going to drive year-round, we will often suggest they do no more than a plus-one fitment because you want to maintain a little more protection for that wheel.â€
Schaefer said he goes so far as to push people toward the other direction, urging them to put smaller wheels on their car when possible. Not long ago, he said, a local college student came into his shop with bent rims three times within a few months after hitting several potholes. He convinced the father to switch to 16-inch wheels from 17-inch ones.
â€œThat was two years ago,â€ he said. â€œShe's ready to graduate and she hasn't had to come back since. She's still hitting the same chuck holesâ€¦. It was less expensive to buy four new wheels and tyres than to keep going with the ones that came from the factory.â€
Chung, however, said dealers need to be aware that reducing the wheel size may not always be appropriate.
â€œGiven the mentioned trend of increasing rim diameters, dealers should note that both vehicle design and engineering have also changed to accommodate as best as possible the tradeoffs in using lower-aspect ratio tyres,â€ he said. â€œA tried and true tyre from the past may not be too compatible with the newer generation of cars.â€
According to Edmonds, many of the perceived problems with low-profile designs could be fixed by educating the public on the importance of tyre maintenance.
â€œThat's one thing that I would have to say shame on the tyre industry, the manufacturers and the dealers,â€ he said. â€œWe haven't done a good enough job. Care and feeding of those tyres goes a long way, and they're probably the most abused part of our vehicles.â€
From Tire Business (A Crain publication)