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2005 Tire Buyer's Guide - Tuner Tech

Tire Test

By , Photography by Josh Brown,

The tires on your car are one of the greatest safety and performance purchases you'll ever make, so read this before changing your tires. We'll tell you which tires are best in the rain, the dry, or both. We gathered 14 of the latest high-performance tires, two racecar drivers, and a couple of BMWs to discover the best performance tires for 2006.

We've all heard people tell us the tires on your car are the most critical purchase you can make. After all, they're the only contact between you and the road, and their ability to grip has far-reaching consequences. Not only can they save your life by reducing braking distances, but they can knock seconds off your lap times - something you'd spend thousands of dollars to achieve with engine tuning.

We all know this, and that's why we go through a rigorous selection process when buying new tires. We inevitably consider performance, cost, reputation, marketing, and even appearance. The problem is, a wrong decision could be catastrophic. So how can we be better informed? Well, you can read our second annual eurotuner tire test and know which are the best tires out there. You can also visit www.tirerack.com because the retailer has its own test facility and scrutinizes every product before offering it for sale.

We wanted to gather our own data and Tire Rack kindly allowed us to use its facilities at the company's HQ in South Bend, Indiana. In addition to an intelligently designed track with a sprinkler system for wet testing, the company also has a fleet of the latest BMW 325i test cars and a sophisticated timing system. So all we needed to bring was a sample of perfor-mance tires and some drivers.

Most of the tires were removed from The Tire Rack's huge stores, so all we had to provide were the drivers. And since we'd be using BMWs, who better to employ than Turner Motorsport's Will Turner and Don Salama? Besides being friends of ours, they share a TMS 330i in the Grand-Am Cup racing series (www.turnermotorsport.com) and flew to our test between races. Having tuned, tested, and won in BMWs, there are few people more qualified to drive for us.

Please don't turn the page if you own a VW, Audi, 5-Series, and so on because the results apply equally to your car. We simply used BMWs because The Tire Rack had decided the cars are sufficiently rugged to tolerate the constant abuse and the rear-drive chassis is nimble enough to provide excellent feedback without introducing understeer. The BMWs have the Steptronic transmission for reliability and consistency, and the traction control was obviously switched off.

The Test
We changed very little from last year's procedure since it worked so well. Consequently, when our drivers first arrived at the track, they were again put behind the wheel of a 325i on control tires. These were 205/55-16 Michelin Energy MXV4 Plus on 16x7.5" Borbet Type E wheels (19 lb). The tires were chosen becuase they were OE spec on 2000-05 3-Series before BMW switched to run-flats on the new E90. The drivers were invited to complete a series of familiarization laps to learn both the track and the car. Times were then recorded before swapping to our test samples.

For the test, we used a common upgrade size - 17x8" wheels (in this case, the ASA AR1 with ET40 but adapted to ET35 with a spacer to suit the E90, weighing 21.2 lb) with 225/45-17 tires. Obviously, we were tempted to go for 18" or 19" wheels, but it was agreed these could introduce factors that may cloud the raw data about the tires' performance.

All 14 sets of test tires were fitted to 56 identical ASA wheels that The Tire Rack keeps for such occasions. They were inflated to 35psi all round for consistency.

Each driver completed three timed laps on each set of tires in both the wet and dry. The fuel tanks were topped up before each session. Wet-weather testing took place on the first day, dry on the second.

To ensure consistency, our drivers tested the control tires several times during the day. If there were large discrepancies, we could assume the drivers had "learned" the track during the day. Yet they were within tenths of a second of their original times, and on occasion just hundredths of a second separated their lap times.

What was amazing to us was the consistency and analytical powers of both drivers. Despite driving 15 different tires (including the control) each day, they were able to estimate their lap times and rank each tire correctly against its peers. To say the event was competitive would be an understatement.

While proving what great drivers they are, it also showed that both were getting the maximum performance from each tire. We then asked for their comments on each tire as they stepped from the car, and as you can see, both generally agreed about the tire's ability. This confirmed we'd not only chosen the right people but that we were getting the right information. The fact they generally agreed with The Tire Rack's own research was an added bonus.

Of course, neither driver knew what tires were on the car before he drove it and when he gave his views on its performance. This was to avoid any chance of bias. We've also found that people drive differently if they've formed expectations about the tire. For example, they might drive harder if they know the tire performed well last year, or vice versa.

If you turn to the results page, you'll see wet and dry figures for the overall lap time. This represents the average of the fastest two laps recorded by both drivers, to show the full potential of the tire. Then there are wet and dry g-force numbers, which show the ultimate grip the tire's able to generate, again taken as an average. You'll also find wet and dry slalom times, which record the time through the lane-change section and illustrate the tire's ability to change direction.

The ambient temperature during our tests varied just 3 or 4 degrees all day, which is not enough to affect the results. However, it was about 10 hotter during our test days than during last year's test, which may partially explain why some tires have scored differently this year.

We also have wet and dry braking mea-surements. The Tire Track's test engineers recorded these using our sample batch of tires on a different day. Brake testing is a demanding exercise that requires the exact same amount of pedal force to be applied at the same point and speed with mechanical consistency. Given Will and Don's lack of experience in this area, we decided to leave it to the technicians.

The brake testing was performed using a Vericom VC2000 Performance Computer that captures entry speed, time to stop, distance to stop, and peak and average g-force. Entry speed is 50mph and the driver makes 10 stops. The average stopping distance is then calculated from this data.

When you look at the results, you'll notice we have color-coded the tires. This is because some of the tires were designed for different usage and we thought you should be aware of this. For example, the first group (yellow) are a more budget-orientated high performance tire. The second, and biggest, group (blue) is the maximum performance tire for wet and dry use, while the third group (green) are really summer tires with focus on dry weather ability. Obviously, this is important to keep in mind when you choose a tire, as you consider your budget, usage and road conditions. With all that out of the way, let's get on with the test.

Turner Motorsport
www.turnermotorsport.com
The difficulty with tire testing is driving a road course consistently for two days and being able to feel and remember the nuances of every tire, both in the wet and the dry. That kind of skill can only be found in experienced race car drivers. So that's exactly what we got. Actually, to be on the safe side, we got two.

Will Turner, owner of Turner Motorsport, and Don Salama, a TMS professional driver, volunteered for the mission. Their racing experience includes claiming the 2003 Speed World Challenge Touring Car championship, plus a string of race wins and pole positions.

Will Turner runs one of the leading independent BMW race teams in the world. He has a total of five BMWs racing in the 2005 Grand-Am Cup, Speed Touring Cup and SCCA T2 series.

Another reason we approached TMS was because TMS doesn't have any specific affiliation to a tire manufacturer. In fact, Will claims he stopped selling wheels and tires a while ago, instead referring customers to Tire Rack. The only association TMS shares with a tire company is Toyo, which supplies the spec tire for the Speed World Challenge Touring Car class and sponsors the TMS M3 in the T2 class. To ensure this allegiance doesn't affect the results, the drivers have no idea what tires are on the car when they run and when they comment on the performance.

We'd like to thank both Will and Don for taking the time to attend our event and putting in a consistent effort to make the test a success.

The Tire Rackwww.tirerack.comThe Tire Rack prides itself on being a well-stocked company with informed employees, and from what we saw during our testing at Tire Rack's South Bend, Indiana, headquarters, we can't dispute it claims. For starters, Tire Rack has a test facility where it tests all the products it sells. That means it doesn't take a manufacturer's claimed performance as fact. If a tire, wheel, or suspension package performs, Tire Rack employees know because they tested it personally.

Every team member spends roughly 80 hours a year in the classroom and testing products. Therefore, when you call to order something, the person taking your order is educated on correct fitments and knows how the product could affect your car.

As for stock, Tire Rack has four giant warehouses across America - in Indiana, Nevada, Delaware, and Louisiana - all stocking more products than you can imagine. In fact, some tire manufacturers use these warehouses as an emergency reserve. For the customer, this means the tire you want is only a phone call away. Check out the website and see for yourselves exactly what they offer, and view the forums to see what their customers have to say about each product.

Reading A Tire SizeA tire's size is usually written as a series of numbers, for example: 225/45-17. The 225 represents the width in millimeters. The 45 is the sidewall height as a ratio of the tire's section width. In this example, the sidewall would be 45% of 225mm, or 101mm. The 17 represents the diameter of wheel in inches the tire will fit.

Reading This ArticleOn the following pages we have provided some specific information about each tire in the test, and here's a brief explanation about what some of the terms mean.

Tread Depth - For the most part, the tires we tested come with 10/32" tread depth. The shallower the depth, the better dry traction it should have, although the life span may be shorter.

Tread Design - There are two designs in our group: directional and asymmetric. Directional tires have a forward-rolling direction, while asymmetric have tread blocks that must be positioned toward the outside of the vehicle. In some cases, there are directional asymmetric tires.

Tread Wear - Tread wear ratings are obtained on a government-specified course, and although the number doesn't mean much, it's useful for comparison. For example, a tire with a tread-wear rating of 200 should wear twice as well as a tire with a score of 100.

Traction - This rating scores only wet braking, and the tire can achieve AA, A, B, or C, where C is the worst. The AA rating was added in 1997 when new tires began to excel in wet-braking tests. Keep in mind, the traction rating doesn't take cornering ability into consideration.

Temperature - The temperature rating is scored as A, B, or C. The tire is scored while properly inflated and the car isn't overloaded.

Uniform Tire Quality Grade (UTQG) - The UTQG comprises the tread wear, traction and temperature ratings. The UTQG is a DOT-required test all tires must undergo to be sold for street use in the USA. The UTQG is clearly printed on the sidewall of every tire. The minimum accepted for our test was a UTQG of 140.

Load Index - This is represented by a number generally between 71 and 110. It's important to note that the load index changes based on the tire's size. For the 225/45-17 we tested, most fell between 90 and 94. A load index of 90 means the tire can support 1,323 lb, whereas a rating of 94 means it can support 1,477 lb. Generally, the smaller the tire, the lower the load index.

Speed Rating - This is achieved by running a tire on a metal drum at the correct load and speed for 10 minutes, then increasing the speed by 6.2mph. Most people view Z-rated tires as the best, but this is outdated. Z-rating means the tire is rated at a generic 149-plus mph, and many people thought there would be no need to rate a tire at a higher speed. However, new tires are rated at V (149mph), W (168mph), or Y (186mph).

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