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Wheel Comparison - Wheel War: 15s VS. 18s

Drivers Side View
Ken Brubaker
| Senior Editor, Four Wheeler
Posted April 1, 2005

Are 18s Bling Or King?

For years, the 15-inch-diameter wheel was the standard for us 'wheelers. It didn't matter whether we were running 31-inch- or 44-inch-diameter tires on our rigs-most of us used 15-inch wheels. Five years ago, the largest wheel diameter advertised in the October issue of Four Wheeler was 17 inches. Most were in the 15- to 16.5-inch range. But times have changed. The Jan. '05 issue of Four Wheeler sported advertising for a number of 18- and 20-inch wheels. Another indicator of the trend towards bigger wheels is seen when looking at the competitors in Top Truck Challenge (TTC). These folks have historically been on the cutting edge of 'wheeling tech, and in 2000, 9 of 10 TTC competitor rigs were equipped with 15-inch wheels. In 2004, the numbers were radically different as seven TTC rigs had 16.5s and only two had 15s. One competitor was running 20s. The OEMs are also jumping into the big wheel trend. Consider that the largest wheel diameter in our 2000 Pickup Truck of the Year competition was 16 inches. In '04, the largest wheel diameter increased to 18 inches, and a couple of rigs were equipped with 17s. Further, OEMs like Dodge and Ford now offer optional 20-inch wheels on some of their trucks.

From showrooms to boulders, bigger wheels are becoming commonplace. But does this new trend help or inhibit our rig's performance? Why would you need a larger wheel? Is the cost of the larger wheels and tires justified? How do the two compare in regards to weight? Could it be that wheel size is ultimately irrelevant in the big picture, or is the 'wheeling public just figuring out something the pioneers knew 150 years ago when they outfitted their wagons with 50-inch wheels?

We wanted to know the answers to these questions, so we tested a few combinations of wheels and tires. We also asked 'wheelers and tire gurus a lot of questions, and we found that discussing wheel size makes some folks as emotional as the Ford vs. Chevy debate (some consider it an abomination).

As you'll soon read, we chose to test 15- and 18-inch-diameter wheels in both 33- and 35-inch-diameter tire sizes. It's a no-brainer as to why we chose the 15s. We chose the 18s because the signs we see in the industry point to this size wheel as being the next big thing (no pun intended). We chose 33- and 35-inch tires because these are popular sizes (and they're the largest we could fit on our test rig). As you will see, tire and wheel width varied. There's not a whole lot we could do about that, as we had to work with what was available at the time testing needed to begin, which was many months before this story was written.

Hopefully, the following data will help you answer the question as to whether larger wheels are bling or king.

Combination tested: 33x12.50R15 Pro Comp Xterrain w/15x10 Pro Comp 1079
Tire/wheel data: The Xterrain is CAD-designed, with directional lugs and deep lug sipes. The tire features Dualguard polyester body plies that consist of thick two-ply polyester construction. The sidewalls feature a blend of dual sidewall rubber, allowing for maximum puncture resistance with total flexibility when using lower air pressure off-road without excessive heat buildup. The Xterrain also features two layers of opposed-angle steel belting that spans the tread area for maximum puncture resistance. Pro Comp says that this opposed-angle steel also allows the tread to flex under lower air pressure to maximize traction off-road. The 15x10 Pro Comp 1079 aluminum wheel has a fully polished face and is constructed using strength-producing counter-pressure casting technology. The optional Xtreme rings give the wheels a rugged bead-lock look, and simply bolt on.

Tire weight (lb.): 53
Wheel weight (lb.): 26
Combined weight (lb.): 78
Overall tire diameter (in.): 32.6
Approximate street price of 33x12.50R15 Pro Comp Xterrain: $202.99
Approximate street price of 15x10 Pro Comp 1079 w/Xtreme ring: $190.98

Combination tested: 33x13.50R18 Pro Comp Xterrain w/18x9.5 Pro Comp 1059129-0504-comp-03 (IMG_9007)
Tire/wheel data: This is Pro Comp's newest Xterrain. While it shares many of the visual design cues with the 33x12.50R15 Xterrain, it differs in a number of areas. First, it uses a three-ply sidewall instead of the two-ply sides found on other Xterrains. It also incorporates two layers of opposing-angle steel belting, along with a full layer of nylon wrapping in the tread area, for six plies of protection. Further, it uses its own specific rubber compound called Xtreme Traction Compound (XTC). Like Pro Comp's 1079 Xtreme polished wheel, the 1059 is manufactured using counter-pressure casting to produce a strong wheel. With that said, the 1059 has an impressive maximum load carrying capacity of 3,420 pounds.

Tire weight (lb.): 75
Wheel weight (lb.): 30
Combined weight (lb.): 105
Overall tire diameter (in.): 33.6
Approximate street price of 33x13.50R18 Pro Comp Xterrain tire: $349.99
Approximate street price of 18x9.5 Pro Comp 1059 wheel: $168.99

33x12.50R15 @ 35 psi (in.): 9.75
33x12.50R15 @ 16 psi (in.): 11.0
33x12.50R15 tread width increase (% ): 13
33x13.50R18 @ 35 psi (in.): 12.0
33x13.50R18 @ 16 psi (in.): 12.5
33x13.50R18 tread width increase (%): 4

33x12.50R15 @ 35 psi (in.): 7.0
33x12.50R15 @ 16 psi (in.): 6.25
33x13.50R18 @ 35 psi (in.): 6.25
33x13.50R18 @ 16 psi (in.): 5.25

Sources

Weld Wheel Industries
Kansas City, MO 64101
800-788-9353
www.weldracing.com
Eagle Alloys
www.aewheel.com
Pro Competition Tire Company
www.procomptire
Toyo Tire Corporation
Nashville, TN
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