Wheels & Tires
What can be said about tires? They're black and round and keep the wheels from touching the ground, right? Actually, they are your only link to the asphalt when you're riding your sportbike. Motorcycle and tire manufacturers spend more time studying how tires interact with the road than any of us can imagine.
The amazing increase in sporting machinery's capabilities owes as much to tire advances as it does to suspension and engine improvement. When it comes to wheels, lighter is always better, but wheels also play an important role in how your bike steers--even how stable it is in a straight line.
Choosing The Right Tire
If bikes have refined their focus, tires have become laser beams directed at very specific activities. Race tires and street tires both benefit from these advances. Race tires are designed to give maxi-mum grip for an extremely limited time. To make things even more specific, they are formulated to work at temperatures only achieved at track speeds. Below those temperatures, they can be downright scary.
The tire companies are even tuning their street tires for different levels of sport riding. If you're the kind of rider who commutes, travels and runs the twisties on the weekend, you'll be fine with the OE tires for your bike. Suppose you're the type of rider that only canyon scratches or attends track days. Well, the premium-model sport tires are what you'll want to run. According to Jeff Johnson from Metzeler/Pirelli, Pirelli's Diablo tires were designed for riders who spend about 30 percent of their time on the track and 70 percent on the street. The Diablo Corsa has someone who spends 70 percent of the time at the track and 30 percent on the street as its intended user. Rubber compounds have gotten that specific.
The best places to find information about who the manufacturers directed a particular tire toward are the manufacturers themselves. They know that, if they're designing tires for specific riders, they need to let those riders know what the differences are.
Instead of worrying about which tire is stickier, you should concentrate on things like the tire profile. Are you the kind of rider who likes to slam your bike on its side and rail through corners at maximum lean? A more triangular profile, with its quicker steering and larger contact patch at full lean, will be more suited to you. If you're a rider who trail brakes into turns, hanging at the outside, waiting to see where the pavement goes before committing to your final line, you should look at rounder profiles that have a larger contact patch for braking while upright and allow for easier adjust-ment of lines mid-corner.
Similarly, you should look into what riders and tire manufacturers recommend for the type of riding conditions you're likely to face. If most of your favorite roads are pretty bumpy, you'll be looking for a tire with a softer carcass to allow the tread to flex over the bumps. If rain is a regular occurrence in your region, pay special attention to a tire's silica content for wet pavement grip. Also, while the big, blocky tread of some hyper-sport tires look sexy, you can end up doing the two-wheel two-step with them in the wet. Some tires have a reputation for taking a long time to warm up in cooler temperatures, so consider the season when you buy new rubber.
Finally, only use tires that are designed to fit on your particular rims. Putting bigger tires on your rim may not give you the bigger contact patch you desire. Since the carcass will be squeezed smaller to fit, the carefully designed profile will be erased.
Aftermarket Wheels
In its most basic sense, installing a set of aftermarket wheels is no more difficult than remounting the stock rims after a tire change or brake disc swap--except for the extra money and massive street cred. Seriously, though, mounting up a set of forged magnesium wheels gets you more than a big credit card bill. Adding lighter wheels can, arguably, deliver the most bang for the buck of any motorcycle modification.
Even though the OEs have wised up and started producing some exceptionally light wheels, any reduction in unsprung weight (weight not supported by the suspension) makes it easier for your suspenders to help the tires track across pavement irregularities. Even saving a couple of pounds here is a big deal. Replace wheels on a bike more than a couple of years old, and you can could save as much as 10 pounds.
Next, consider the weight of the wheel at its rim. As Kevin Cameron says in Sportbike Performance Handbook, "A pound saved in a wheel rim...is worth 2 pounds anywhere else on the machine. A wheel has to be accelerated twice; once in a straight line, and also in the second sense of rotating around its own center." Since wheels rotate, generating gyroscopic forces, a lighter wheel will turn quicker and accept steering inputs more readily. Riders who like flicking their bikes into turns will love the effect lighter wheels have on steering.
source: superstreetbike.com
