{There has been a definite trend in pickup tires to lower profile and larger diameter, the main effect of which has been much more money spent compared to the old traditional 15 inch diameter 85 profile pickup tire. Progress is not always good. It is a shame that Dodge, Ford and GM pickup owners today can't lend a friend in need a "standard" 5 on 5.5 pickup wheel after a flat like they could in the 1970s.}

Slim tires too cool to be safe?
The low-profile look exudes sex appeal and is selling well, but it's also pricey and a bit fragile.
By Ralph Vartabedian
LA Times Staff Writer

August 23, 2006

More and more motorists seem to be driving around in cars sitting atop what look like rubber bands: low profile tires on giant alloy wheels.

Those "rubber bands" are actually high performance or touring tires, and they're wildly popular among consumers who like a muscular, sporty look.
But like an injury-prone star athlete, the buff body disguises some weaknesses. If you don't think so, just ask Los Angeles County Superior Court Judge Lance Ito.

Ito wrote to me recently about his two Audi A6s, whose low aspect ratio tires have had nine flats in the last 40,000 miles. He has gone through three sets of tires in that time. "I will never again buy a car with these low-profile tires," Ito said. You can almost hear his gavel bang.

In fact, engineers and safety experts say low aspect ratio tires — which have shorter sidewalls — are more vulnerable to road hazards, such as potholes and other obstructions that can test a tire's ability to flex at high speed, than their standard counterparts.

Officials from Goodyear, Michelin and Bridgestone — the three largest tire makers — all acknowledged in interviews that their low aspect ratio tires are more likely to be damaged by impacts in normal driving.

"They are more susceptible to pothole damage," said Bill VandeWater, Bridgestone's consumer tire products manager, in Nashville. "They don't have as much give before the tread contacts the rim. There isn't as much deflection capability as a taller tire."

What can you do about it? Well, advice from manufacturers can be kind of silly. Take, for example, Volkswagen's suggestion. "Avoid driving on roads with potholes, deep gouges or ridges," it tells owners of cars equipped with these tires. In other words, keep the car in the garage.

Nonetheless, consumers like the look. At Michelin, 20% of the tires it sells are high performance, and that figure is growing by about 10% annually, while sales of the standard "mass market tires" for cars are shrinking, said Lynn Mann, director of public relations for the tire maker.

Although consumers like the low-profile tires, safety experts are dubious about their practicality.

"My observation, other than styling, is why have them?" asks Clarence Ditlow, executive director of the Center for Auto Safety in Washington, D.C. "My advice to consumers is don't buy them."

Perhaps. But many don't have a choice. Manufacturers are offering autos with wheel wells designed to fit only a low aspect ratio tire, especially luxury cars with a sporty image.

Purchasing tires has always been a mystery to many motorists. When you buy a tire, there are three keys to its size: tread width, rim size and aspect ratio.

For example, a 205-65-15 tire has a 205 millimeter tread width and fits on a 15-inch rim. The 65 is the aspect ratio, a measure of a tire's profile. It is measured by taking the diameter of the tire, subtracting the diameter of the rim and then dividing by the width. The actual ratio in this example is 0.65, but typically described as 65.

To put it simply, the lower the aspect ratio, the shorter the tire. At one time, most tires had ratios of about 70 and rim sizes of 13 to 15 inches. Then, aspect ratios began to drop and wheel rim sizes began to grow.

Now there are rim sizes up to 24 inches and aspect ratios down to 25.

"It almost does look like a rubber band around the wheel," VandeWater said.

What's the point of this madness, other than sexy appearance? Ultra high performance tires almost always have low aspect ratios. These tires have speed ratings up to 186 miles per hour, super soft rubber that grips the road and construction that gives positive steering.

"It is meant for those people who see the freeway exit sign that says 40 mph, and they get that gleam in their eye and think: I bet I can do it at 80 mph," VandeWater said.

On their highway to heaven, however, these drivers are finding they have to change tires every 20,000 miles. And the ultra high performance tires are like ice skates on cold road surfaces, plus they cost a fortune to replace.

To get the same cool look but greater durability, manufacturers offer what they call touring tires. They have the low aspect ratios, but harder rubber that lasts longer. They also have a little more forgiving ride that doesn't report every pebble on the roadway.

Unfortunately, all low aspect ratio tires, both ultra performance and touring, are vulnerable to road hazards. And they are more vulnerable to under-inflation, many experts say.

"The lower aspect ratio makes it more sensitive to low inflation," said Max Nonnamaker, a tire expert and former chief engineer for a tire maker. "When the tire is taller or higher, you can lose more air. Any drop in pressure is more critical, because there is a shorter sidewall and you generate more heat."

An under-inflated tire flexes more as it goes down the road, generating more heat in the sidewall, which eventually can cause internal damage. Thus, keeping an eye on inflation is critical. But Ito said he checked the pressure in his tires two or three times per week and still experienced problems.

Tire inflation is always a controversial subject. Every tire has embossed on its side a maximum inflation rating. That's different than the the car manufacturer's recommended inflation, which is always less.

Nonnamaker believes that tire manufacturers should be required to also list a minimum inflation rating, below which tire damage occurs. But no tire maker wants to list such a rating. They could certainly do so voluntarily.

VandeWater said he believes that damage can occur if inflation drops 5 pounds below the level recommended by the carmaker. Typically, recommended inflation is 32 pounds, so you would be causing damage at 27 pounds. It is a tiny margin that very few consumers appreciate.

In a future column, I'll examine how the promise of tire pressure monitoring systems, which would warn drivers of low air, have failed to deliver useful technology to consumers.

*Contact Ralph Vartabedian at ralph.vartabedian@latimes .com

 

Therefore, do not drive in Pennsylvania where the DOT advertises a pothole hotline that you can call to report potholes - like the entire section of Route 80. Also, they would rather install "Bump" signs rather than fix the road. [:@]

 

I often find it funny when guys buy pick-up trucks or large SUV's, and then because they think it looks cool, put large rims and low profile tires. Then, that one weekend comes along when they need to use their truck like a truck or tow with that SUV, and they load up to the max the vehicle is rated for. To bad the tire is no longer rated for the same. Not only do low profile tires damage easier as addressed in Hanks post, but they also do not have the load capability, you need sidewall to support heavy loads.

 

even if i had a sports car i would never use low profile tires...... my buddy has some on his car and their scary in the rain..... plus his are bald (down to the bar) and he hasnt replaced them yet

 

Big rims n rubber bands do have a cool factor but arent that practical depending on the roads where you live/drive. Few guys I know busted rims, damaged suspension and blew out tires.

Bigger rims reduce performance and increase braking distances.

Part of the reason Ive resisted going bigger so long. Tire wear is the other reason, though as it turns out the 20k per quoted above is much better than I ever get lol. Just under 60k miles Im on my 4th set of street tires, 3 set of slicks and going onto my 2nd set of skinnies. Ill probably go to 20s on the street next year to slow my 96 down a bit(15" Draglites for the track). Oh, only thing I have ever had in the 96's bed is race rims/rubber and floor jack or performance parts. My V10 is for haulin so its not an issue for me

 

The ONLY question I'd have for Ito is this ... How in the HELL did you manage to let OJ get away with it ??

 

think nascar... think any racing sport... see their tires? see the side wall they have?? think that they do over 200mph... why the hell would you want to put "performance" rubber bands on your car/truck/suv doing 60mph? yeah if you did, don't drive that car... don't go over any railroad tracks...

hmm there is a reason they put large rubber and smaller rims on those race cars... FEW BLOWOUTS, FLEX, LOAD, AND ALL THAT!!!

sorry this is a really annoying thing to me. i like large rims i do really i do, but only if they've got FAT meats on them. i would love to run 20's with a 40" tire.. oh i like that look.


PERFORMANCE >>>>>>>>>>> look...

 

I've always figured that larger rim = shorter sidewall = less flex = faster steering input.

I don't have any of this stuff on any of my rides though. I always go as big as I can on tires. Larger footprint = more traction.

Hooray traction.

 

Low profile tires are great on my sports car. I run 285 wide 30 series summer tires and have no problem in any weather except snow and I still do okay if I accidently get caught in it.
On my truck I would never consider going low-profile. I'm looking for nice rims right now but the biggest I would go is 17". I bought my truck to be - well - a truck!