Tom Wilson
December 1, 2003

Touch a tire and you get grimy and black. Look at a tire and it's dull and grimy and black. Run a tire hard and it turns the pavement grimy black. But bolt on a fresh set of tires that are well-matched to your ride and they're golden. In fact, no other single part on your car makes such a performance difference nor is as vital to your automotive enjoyment or safety as those four grimy black donuts that provide the all-important contact patches with terra firma. But being grimy black all the time, tires typically don't get the respect they deserve.

That's definitely not the case at The Tire Rack in South Bend, Indiana. There, tires are king. From a mind-numbing selection to same-day shipping, tires are the focus of every effort at The Tire Rack.

That's why we jetted to South Bend when we wanted to illustrate the range of street-tire performance available these days. Without a doubt, modern tires offer impressive performance, but they also represent a major investment. With so many tire brands and styles available, guidance on which is the right tire is the best place to start.

Two IdeasCost is an obvious criterion when selecting tires, so we worked with Matt Edmonds and John Rastetter of The Tire Rack to build a test that would illustrate the entry, middle, and upper edges of the high-performance street-tire market based on tire price. This range of real-world performance street tires is easily where the action is, and that's why we didn't bother with low-buck specials, wallet-excoriating, ultra-high-performance tires, or the track-oriented, super sticky, fast-wearing race tires sporting just enough tread to muster DOT approval. Those are another story altogether.

It's also important to understand the tires tested here are not the only-or necessarily even the best-choices for any particular application. Instead, these tires are a cross-section, a representative set of price ranges and brands designed to show what range of performance differences you can expect in this class of tires.

We also had another idea, that of going plus one or plus two in wheel diameter. Moving from 17- to 18- and even to 19-inch diameters is almost as common in the Mustang world as replacing worn tires, so we wanted to take a careful look at what such moves gain. Because The Tire Rack also sells wheels, putting that test together was a snap.

Naturally, we wanted to use Mustangs for our testing, and Ford SVT helped us out with the loan of two '03 Mustang Cobras. With the logistics thus handled by The Tire Rack and SVT, all we had to do was show up and drive. Life was good!

Arriving on CampusHere's the real kicker. Not only does The Tire Rack have half a million square feet of tire warehouse to draw from, but there's also a dedicated tire test track built into the front lawn. Purpose-built for tire testing, the short, modified figure eight was precisely what we needed to objectively test several tires. Given the track is outfitted with a timing system yielding overall and segment times, as well as a sprinkler system for wet testing, we were set to acquire all the data we could handle.

Additionally, The Tire Rack uses several miles of public roads surrounding the plant for noise, ride, and other real-world evaluations. These tests follow a set pattern-radio off, ventilation fan no higher than the lowest setting, windows up, posted speed limit, and so on. This maximizes the tires' input and provides repeatability. The roads vary from new to old, surface streets to freeway, and concrete to asphalt.

Same Size, but DifferentFor our first test, we tried three dif-ferent brands of tires, all in the same 275/40-17 size standard on current Mustang Cobras. The three tires and their details are as follows.

All these models are high-performance tires, so all are crafted to return good steering feedback to the driver and could be expected to trade some noise and ride comfort for performance. John Rastetter briefed us using the existing Tire Rack notes. The Kumhos should prove the softest of the three in carcass construction, so there might be some "squish" in their feel, yet still with good controlla-bility. Such a tire might respond favorably to more tire inflation, too, as the carcass would provide relatively less support (this parameter was not tested). Also, as Kumho is relatively new to the U.S. market, it has gone for aggressive dry-pavement grip as this gets the most headlines in the enthusiast press. The company wants to showcase its abilities against the more estab-lished brands.

The Goodyears promised excellent balance between wet and dry handling thanks to a tread design biased more to wet traction than is usual in many performance tires, including the other two we were trying. Its carcass construction is more developed as well, with resulting great steering feedback.

The BFGs, the notes said, would feel much like the Goodyears, but with more emphasis on dry traction, so we should not expect them to set records in the wet. They feature more rounded shoulders with smaller grooves, so in the wet they should respond predictably up to their limit, then break traction more briskly.

With that in mind, we hit the track in light rain with the track sprinklers running. The 12 tires were mounted on their own sets of wheels, so changing from one tire to another was easily done by swapping sets. We ran through all three brands, beginning with the Kumhos. We then reran the Kumhos at the end of the test to verify our first results, checking for variables (such as a drying track, tire wear), and most importantly, to get a check on the inevitable gain in speed we'd exhibit after learning this new (to us) track.

It didn't take more than a couple laps to show The Tire Rack testers are one buff bunch of drivers. In contrast to our slow, marginally consistent laps, John and his assistant John Rogers (known as Woody) knocked off a string of fast, deadly consistent laps. It was a most impressive display of driving talent and discipline on their part.

Furthermore, it would take this entire article to display all the lap-by-lap data collected by the timing system, but we have room for only the highlights. The data is organized such that John and Woody's close and consistent efforts are combined in the left column and my slower efforts are segregated into the right column. The best (fastest) of both segment and total lap times are presented in seconds, and the g's produced on the skidpad portion of the lap are shown.

Additionally, because there were several trials (laps) by each driver on each tire, the timing computer was programmed to give an average of the segment and total lap times by ignoring the slowest half of the laps and averaging just the fasted half of each set of laps. In other words, if a driver ran six laps on one tire, the slowest three laps would be ignored and the fastest three laps would be averaged. This average infor-mation is the best information, in our opinion, because it uses the longest baseline to acquire the data, it totally ignores the dumb laps where overt driving mistakes skew the data, and it somewhat suppresses the fluke fast laps where somehow it all comes together for one magic lap.

At the end of the data, the change (variance) between the first run on the Kumhos to the second quantifies the track and driver variables discussed earlier.

There is interesting data when you pour over it (see Wet Testing sidebar). Above all, it takes good drivers who are familiar with the track to consistently return useful data. John and Woody were doing the real work, while I was learning the track and discipline required. Examining the differences between best and average runs illustrates that point.

Also, the g loads built on the skidpad certainly vary by driver. Keep that in mind when reading the data panels in road tests on new cars and so on. There's no sense in sweating over 0.01 g when there's 0.03 difference between drivers.

Remember, this first set of data is from wet testing, and the 0.92 g returned by the Goodyears has incredible grip in the wet. In terms of times, the Kumhos and BFGs are not that far apart. Curiously, I was a tick quicker on the Kumhos, while John and Woody did their best with the BFGs. To each his own, we suppose. Could this be a case of one driver relating to a certain form of feedback from a tire while other drivers respond favorably to something else?

As for feel, John's pretesting advice on how each tire would run and respond was spot-on. The Kumhos were the softest of the three in carcass squishiness, and yet still OK in controllability. The Goodyears were easily the best tires of those present. They were predictable and easy to drive, giving great input to the driver right up to the limit and then staying on the job should you exceed the limit and fight to regain control. The BFGs felt much like the Goodyears, but with generally less grip on the sloppy track. Furthermore, they gave up more abruptly at the limit of adhesion, and then didn't come back to gripping as quickly as the Goodyears. You might say they were uncatchable when getting carried away with tossing the car from side to side.

It's interesting how each brand of tires has its own grip personality. The Good-years, for example, had a chunk, chunk, chunk type of traction around the skidpad, a sort of light ratcheting. The other two tires were considerably "softer" in their orbits around the skidpad.

And, even though we were expecting it, it's amazing what differences you can feel in tires when comparing them back-to-back like this. You'd never get such precise intelligence via the usual routine of buying a set every three years or driving your buddy's car, or whatever. Even the data, though accurate and pointing in the right direction, doesn't convey the notable superiority of the Goodyears in behind-the-wheel experience in this wet test.

On A Dry TrackThe next day dawned with no rain, so we repeated the first day's tests in the dry. What a difference!.

For starters, in the rain it's nearly impossible to hurt the tires by spinning the rears or understeering the fronts, but in the dry, a ham-fisted driver can do real rubber damage. The same goes for the brakes, which really didn't have to earn their keep until the track dried. Secondly, the wet driving almost seemed easier as we had to acclimate to higher speeds and more precise judgment required by the dry track. Some of this was because of the Cobras-with their Roots-blower torque, they still required careful throttle modulation to avoid wheelspin. But most importantly, the tires themselves changed personalities when the sun came out.

Foremost of these were the Good-years. The clear champions in the wet, in the dry the Eagles felt squishy in the technical sections, exhibited low-grip on the skidpad, and were too easy to give up everywhere. The bright side was a progressive loss of grip, so the breakaway characteristics were benign. But the biggest surprise was the Good-years' squirminess in the dry. Com-pared to their clear wet-traction superiority, this was a huge change.

The Kumhos were a little squishy on the skidpad and responded to a bit of understeer bullying there. In transitions, the Kumhos were OK, but not as crisp as we would have liked. Going along with their soft-edged personality, the Kumhos gave up grip in an easy-to-handle progression.

The BFGs took the dry-pavement crown. They proved much more secure and produced more precise steering than the Goodyears. The BFGs were predictable and able to hang onto the skidpad with authority. They proved edgier than the Kumhos, yet with good predictability and quick return to traction if you pushed them too hard, then backed off. That made them forgiving, and with the best traction of our trio, the easy pick for dry pavement.

As you inspect the data, note how the track was approximately 2 seconds a lap faster than in the wet. That's a major change in a lap that's only 30 seconds to begin with. Also keep in mind that Goodyear was clearly looking for a great all-around, all-weather tire and got it, while BFG was clearly specializing in dry traction, and Kumho nearly the same, but with more of a nod to wet traction too.

Road TestFinally, we were able to take the Kumhos and the Goodyears on The Tire Rack's 10-minute driveability loop on public roads.

The Kumhos were hard riding and offered a low-frequency rumble. The Goodyears were notably softer in ride and much quieter on the low frequency. Instead, they had a high-pitched "sing."

Again, in back-to-back trials such as this, variations stand out clearly, something that simply isn't possible without a controlled test.

Different Size, but the SameOur second major test, sampling the same make and model tires in 17-, 18- and 19-inch sizes, was easily conducted in the last half of the second day. Again, we had multiple sets of wheels and tires mounted and ready to swap at our disposal, so the testing was conducted about as fast as we could all make several laps, then have the tires and wheels swapped.

The Kumho 712 tires were selected by John because they offer good, if not class-leading, grip at a low price. "A remarkable value" is how Woody characterized the tires. We found the 712s to be notably less grippy and precise than the ECSTA MXs we used in the first test-as expected from a $40-less-expensive, lower-performance tire.

The stock Mustang tire size was mounted on our Cobra's stock rims, while the two plus sizes were mounted on Mille Miglia EV-S wheels as sold by The Tire Rack. The lineup specifics are as follows.

The benefits of plus sizes are that the shorter tire sidewall is faster reacting and more precise than a taller sidewall. Also, the contact patch grows larger, and thus traction is enhanced because the tire typically grows in width when moving to a plus size. Note, we said "typically." Unfortunately, when Ford increased the standard Mustang Cobra tire to a 275 tire, that used up all the width the Mustang fenders and wheelhouses will allow. Therefore, when stepping up to an 18- or 19-inch tire, the sidewall shortens but the contact patch does not grow because a slightly lower aspect ratio tire is used with each gain in wheel diameter. So, the tire grows shorter in the sidewalls, the tire diameter remains the same, and so does the area of the contact patch. Thus, on late-models, the only gain besides cosmetics is in rim diameter. Non-Cobras gain more, as they typically can step up one tire width as well as a lower sidewall when making a plus-one move. After that, it's all in rim diameter.

With that understood, you can see how the only perceptible change in our three wheel-and-tire combinations was an increase in steering precision as the rim diameter increased. The cornering grip, speed, or g's did not increase, and the lap times were consistent throughout the test. In fact, John and Woody went fastest on the 17-inch combination, if only by a whisker.

This is not to say the taller rims aren't more fun. They offer better feel through transitions, and for that alone they're more enjoyable to drive. Of course, on the other hand, there's an inevitable increase in ride harshness with the larger rims, although on the smooth Tire Rack test track we couldn't feel any difference. That's what the public road loop is for, but we didn't have time for that.

What We LearnedWhat stood out to us after our visit was the inexhaustible supply of variables in something as seemingly simple as making a tire selection. While most of the differences in tires don't show up until the extreme edges of performance-it's the road loop, not the test track driving, that matters in the real world-that's just where performance enthusiasts become interested. Mix the cars, tires, drivers, road surface, and weather variables and you can have as much fun choosing tires as you do camshafts.

Also, the lack of change in performance with the taller wheels caught us by surprise. We've always associated the larger rims with more cornering force, but we now see that's true only when the tire improves, or at least gains size.And driving a pair of Cobras for two days wasn't bad work either.

Wheels And Tires

Size Manufacturer Type PRICE Size Manufacturer Type Price
275/40-17 Kumho MX $147 ea. 17x9 Ford SVT Cobra $175 ea.
275/40-17 BFGoodrich KD $269 ea. 17x9 Ford SVT Cobra $175 ea.
275/40-17 Goodyear F1 GSD-3 $185 ea. 17x9 Ford SVT Cobra $175 ea.

Dating the Cobra TwinsWe hoped to get a single '03 SVT Mustang Cobra from the SVT press fleet, but SVT did even better, providing us with two. This sped testing by saving tire-changing time.

We used the gray car (foreground) for the majority of lapping because it had more miles on it, and we used the blue Cobra for the shorter-wheel-diameter comparison. Still, mileage was laughably low. The gray car had 9,000 miles on it at test's end; the blue car had only 1,000 miles.

The Cobras were great tire testers thanks to their massive low-end torque that allowed aggressive rotation and acceleration around the slow turns, along with all the speed the tires could handle in the one higher-speed transition.

Wet Testing

John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best 4.566 4.111 0.839 31.889 4.566 4.242 0.788 32.557
Top 11/42 Average Top 11/42 Average
4.596 4.111 0.839 31.921 4.693 4.248 0.786 32.956
Goodyear eagle F1 GS-D3 Goodyear eagle F1 GS-D3
John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best 4.246 3.921 0.922 30.223 4.336 4.152 0.822 30.746
Top 11/42 Average Top 11/42 Average
4.294 3.931 0.918 30.373 4.386 4.152 0.822 30.809
BFgoodrich g-force T/A KD BFgoodrich g-force T/A KD
John/Woody Tom Wilson
Slalom Skidpad Avg. gs Total Lap Slalom Skidpad Avg. g's Total Lap
Best 4.386 4.042 0.868 31.212 4.386 4.192 0.807 32.023
Top 11/42 Average Top 11/42 Average
4.416 4.060 0.860 31.342 4.436 4.212 0.799 32.118

Kumho ECSTA MX (retest) Kumho ECSTA MX (retest)
John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best 4.446 4.092 0.847 31.609 4.656 4.152 0.822 31.834
Top 1¼2 Average Top 1¼2 Average
4.514 4.125 0.833 31.804 4.661 4.187 0.809 31.988
Variance to round no. 1 Variance to round no. 1
John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best 0.120 0.019 -0.008 0.280 -0.090 0.090 -0.035 0.723
Top 1¼2 Average Top 1¼2 Average
0.082 -0.013 0.005 0.117 0.032 0.061 -0.023 0.969

Wholesale ScaleWe were a bit underprepared for the size of The Tire Rack. The company's South Bend headquarters is an amazing 500,000-square-foot (11.5-acre) tilt-up warehouse with a front office, reception area, and a small retail mounting facility in one corner. The rest is tires in racks-lots and lots of tires in many, many racks.

The front office facilities are large and first-rate without being ostentatious. Besides the 85-person sales office, accounting department, and so on, there is a great 50-plus-seat classroom with full audio/visual capabilities, and a huge photo studio. The classroom is used both to instruct salespeople (each receives eight weeks of training, including hands-on tire testing, before taking their first phone call) and is loaned to car clubs that rent the test track on weekends for slaloms. The studio helps produce catalogs and The Tire Rack's Web-based system, where you can virtually install different wheels on a vehicle.

In the immense warehouse, the goods are organized by fast-moving tires toward the front, then slower movers in the rear; and not by size or make.

Fascinating computerized equipment, including many of the forklifts, move tires via automated conveyor belt and into the backs of a waiting fleet of UPS semitrailers. The trucks head to Chicago and other cities so as not to clog the UPS system, and to give the tires a head-start in the shipping procedure. Three other Tire Rack warehouses in the United States help provide more than 90-percent two-day shipping.

Additional services are tire shaving and heat cycling. These road-racing tire preps are quite popular with racers who can extend tire life, save track time, and receive race tires at their optimum grip level right off the UPS truck.

Testing: Front and CenterIt may appear compact and unusually shaped at first, but The Tire Rack's test track is one crafty bit of macadam. Situated immediately in front of the South Bend headquarters, the track is quickly accessible and outfitted with excellent data-acquisition equipment.

The figure-eight layout evens tire wear by working both sides of the vehicle equally per lap. Each turn is different-some subtly so-but all were carefully designed to extract specific information from the tires. The incorporation of a 200-foot-diameter skidpad into the lap is especially helpful in determining grip, and it's exactly the sort of turn impossible to find outside of a purpose-built track.

Track width is 33 feet, but it is always run with cones set 11 feet apart down the middle. This gives 11 feet of asphalt runoff on either side of the "test lane"-just enough to get an errant car slowed down before it hits the grass. It also means the driving surface is just 11 feet wide-1 foot narrower than a freeway lane. That clearly enforces driving discipline to reduce driving variations, but it does allow a surprising amount of aggression. The track feels like a cross between an autocross and a road-racing track. It allows hard driving while still enabling the driver to feel what the tires are doing instead of merely hanging on at 120 mph. We found the steady pace around the skidpad the easiest area to assess the tires' personalities. The slalom was toughest, the higher speed transitions were the next easiest after the skidpad, and the 90-degree corners were somewhere between the slalom and the skidpad.

Rotating lawn sprinklers provide an evenly wet track when desired. The water system is centrally controlled and can be started or stopped in seconds. A 1-degree slope in the asphalt ensures the water runs to the outside for even wetting.

A built-in set of lasers and reflectors shooting across the track gives lap and segment times, the latter useful in sorting out why speed is made or lost. Built by Crest Industries (popular with auto-crossers for timing gear) the timing system sets up with minimal hassle. The laser heads must be set out and collected each day, but the reflectors are permanent. Data is collected in a laptop, and a controller box controls the clock function.

DRY Testing

John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best 3.981 3.749 1.009 28.917 4.221 3.989 0.891 30.057
Top 11/42 Average Top 11/42 Average
4.127 3.824 0.970 29.082 4.258 4.036 0.871 30.175
Goodyear Eagle F1 GS-D3 Goodyear Eagle F1 GS-D3
John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best 4.082 3.809 0.977 29.131 4.172 4.059 0.861 30.059
Top 11/42 Average Top 11/42 Average
4.131 3.864 0.950 29.387 4.177 4.074 0.854 30.102
BFGoodrich g-Force T/A KD BFGoodrich g-Force T/A KD
John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best 4.072 3.779 0.993 28.783 4.262 4.029 0.873 29.896
Top 11/42 Average Top 11/42 Average
4.099 3.812 0.976 28.926 4.277 4.039 0.869 30.009

Kumho ECSTA MX - Retest Kumho ECSTA MX - Retest
John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best 4.071 3.789 0.988 29.103 4.201 4.009 0.882 30.118
Top 1¼2 Average Top 1¼2 Average
4.096 3.812 0.976 29.225 4.296 4.044 0.867 30.220
Variance to Round No. 1 Variance to Round No. 1
John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best -0.090 -0.040 0.021 -0.186 0.020 -0.020 0.009 -0.061
Top 1¼2 Average Top 1¼2 Average
0.030 0.012 -0.006 -0.143 -0.038 -0.008 0.004 -0.045

PLUS size comparison

17-in Tires/Wheels 17-in Tires/Wheels
John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best 4.212 3.929 0.918 29.813 4.351 4.159 0.820 30.969
Top 11/42 Average Top 11/42 Average
4.255 3.944 0.912 29.898 4.381 4.209 0.800 31.589
18-in Tires/Wheels 18-in Tires/Wheels
John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best 4.211 3.939 0.914 29.895 4.301 4.199 0.804 30.888
Top 11/42 Average Top 11/42 Average
4.236 3.949 0.909 30.031 4.356 4.204 0.802 30.967
19-in Tires/Wheels 19-in Tires/Wheels
John/Woody Tom Wilson
Slalom Skidpad Avg. g's Total Lap Slalom Skidpad Avg. g's Total Lap
Best 4.202 3.919 0.923 29.915 4.282 4.139 0.828 30.574
Top 11/42 Average Top 11/42 Average
4.229 3.954 0.907 29.962 4.307 4.149 0.824 31.047

Plus Comparison

Size Manufacturer Type Price Size Manufacturer Type Price
275/40-17 Kumho 712 $107 ea. 17x9 Ford Ford O.E. N/A
275/35-18 Kumho 712 $158 ea. 18x9 Mille Miglia EV-S $239 ea.
275/30-19 Kumho 712 $210 ea. 19x9 Mille Miglia EV-R $269 ea.

More Than TiresWhile The Tire Rack stocks an immense selection of tires at warehouse prices, the company also offers select associated parts. These include brake pads, shocks, and springs. Its wheel business is huge as well.

However, we've come to see The Tire Rack's unique advantage as information. A fleet of BMW sedans and SUVs is kept on hand for tire testing, and each salesman has the accumulated data and notes from years of ongoing testing at his fingertips. He also has his own firsthand drive evaluations and keeps those notes at hand as well. To our knowledge, such a large volume of cross-brand testing is unique in tire retailing. It's a fabulous resource when choosing a tire.