Our team has used 6" pneumatic wheels the past couple of seasons, but I’ve noticed I see VERY few other FRC teams using these. We’ve noticed a really big percentage of teams using Colsons. I’m debating taking the plunge on these and getting some. We’ve generally liked the really high grip of pneumatics and slight give - is there a reason these seem to be relatively unpopular?
They are heavy and require greater reduction.
The way I see it, there are a handful of choices you have among wheels. Price, live axle vs dead axle, etc. But the most major technical choice is grip vs. life/consistency. The higher grip your wheels are, the faster they tend to wear down. For example, looking at AM HiGrip wheels, you may never have to replace white HiGrips, while you may replace blue HiGrips twice an event (estimating.) Colsons have fairly good grip while not being worn down very quickly. This makes for good robot performance while designing for maintainability, and importantly, autonomous. 0.1" diameter difference could easily be the difference between a 2 and 3 cube auto.
As to the other effects, Colsons are usually bought as live axle wheels from Vex, which makes them easy to use on WCD style drives. This, and some amount of cargo cult engineering, is probably the most major reason why they’re so widespread.
Pneumatic wheels are generally fairly inconsistent (diameter dependent on tread wear and pressure) and not well suited to WCD. So you don’t see them as much, especially on the coast, unless the situation calls for it (ie Stronghold.)
By all means, if they work for you, then carry on. But if you want to step up your game, don’t look so much at products as much as process.
As mentioned before, pneumatic wheels aren’t terribly common due to their inconsistency, size, and difficulty to control.
When considering what wheels to use, it pays to mess around/ test different wheel sizes and types, and find one that your team (especially drivers) feels comfortable with.
Wheel selection needs to be wholly dependent on the requirements of the game and field. Don’t pick your wheels yet.
Here are some criteria to consider:
*flat field with no obstacles, smaller wheels lighter, less money.
- smaller wheels can be mounted closer to the ends of the robot for stop-start stability.
*Big wheels are better for speed if field even a little uneven. .
*Pneumatic wheels are only necessary when you’re bumping. Heavy.
*Wheels often come with the tires, so the amount of traction you’ll get will be dictated by the type of wheel–for instance “plaction” wheels are probably the stickiest wheels you can get, but their very specific diameters and widths. Not available in 4" diam.
*some teams are 3d printing wheels with some success.
*special drive systems like mechanam, omni, need special wheels.
*“regolith” needs special wheels. Hope we don’t need to think about this this year…
*swerve usually needs smaller wheels.
*tank treads are useful sometimes.
*I want to see robots with feet too, no wheels at all. When they come, I think they’ll dominate some games.
71 sorta had feet in 2002 and they did dominate. Unfortunately that same kind of foot is no longer legal.
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Just as a data point, 1519 also uses 6" pneumatic tires/wheels for a lot of our robots. For the reasons you mention (high grip and slight give) they are a good choice for many games. They have been our standard “tank drive” robot tire in 2018, 2016, 2014, and 2012. (Hey, I didn’t realize we’ve only used them in “even year” games. Maybe we won’t be using pneumatic tires this coming year?)