Motorcycle owners, particularly those of the cruiser and chrome variety, often like to keep their rides clean and shiny. From Sturgis and Laconia to your local bike night, the glare off these polished bikes can be downright blinding at times. But you won't see the tires on these motorcycles glimmering in the sunlight with tire shine products, despite tire shine's popularity on cars. And there are good reasons for this.
Shiny tires look slippery because they are slippery. That's why tire shine manufacturers say not to apply their products to the tread area. Unlike a car tire, nearly all of a motorcycle tire's surface is the tread area. If you shine up the edges of the tires, then lean hard into a corner, you're leaning into the area of reduced traction precisely when you need traction the most. When it's not there, this leads to a slide at best, and a crash at worst.
Justin Hughes/Jalopnik
Why is it perfectly fine for auto detailers to make those sidewalls shine while it's a serious hazard for motorcycles? For one thing, cars don't generally tip over if the tires slip a little bit. Bikes do. More important, though, are the different designs of each tire. Car tires are squared off, with distinctly separate vertical sidewalls and flat tread areas — so unless it's severely underinflated, a car tire's side will never touch the road. Motorcycle tires, on the other hand, lean over onto their sides all the time. It's the fundamental nature of how bikes turn. These tires have a round tread profile to help them do this, leaving them with almost no sidewall at all.
This is a photo of the Shinko 705 tire on my Suzuki V-Strom 650. Even this relatively tall adventure tire has a rather short sidewall, which is the section with the "rotation front" writing and the arrow. It's barely thicker than the rim. The entire rest of the tire is the tread area.
A common misconception is that motorcycle tires lean onto the sidewall by design, but this is not true. Despite their round design, the tread and sidewall are different areas with different purposes, just like with a car tire. When a bike leans, it's still riding on the tread, not the sidewall.
Here's an example of what not to do. The owner of this BMW G310R attempted to shine up the sidewalls and instead spread tire shine partway across the tread. Tire shine manufacturers, from no-name Amazon brands to quality brands like AvalonKing, all warn you not to apply their products to the tread because it's slippery, which is the opposite of what you want.
Besides, when the vast majority of the tire is tread, is it even worth trying to shine up the small, narrow strip of sidewall? It would look different from the rest of the tire, and the mismatch could look worse than leaving it alone. The chance of getting some slippery tire shine on the tread isn't worth it, especially when you're leaning hard into corners trying to get rid of your tires' chicken strips. That's the worst possible time to lose traction because you want your tires to look good.
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