4" vs. 6" vs. 8" wheels. Advantages?

[BJC]

Originally Posted by billbo911

I've searched and I really didn't find any discussions that directly answer these questions. If you know of a posting or white paper that addresses these questions, can you please post a link to it, otherwise, what are your thoughts, and why?
I've read through several white papers, but none seem to address these specific questions.

If gearing was appropriately matched, what are the advantages and disadvantages of the various diameters of wheels? Does the width of the wheel really matter that much?

I think I can help you out a little. The width of a wheel does matter. A 1" wide wheel has half the contact patch of a 2" wide wheel. ex: You don't ever see dragsters with thin wheels. They always have very thick wheels giving them a higher normal force so they can take off faster. That said, with FIRST robots it is a pretty small difference. If you are looking to increase your traction, you should look for wheels with a higher coeffient of friction. As far as I know pneumatic wheels have the highest CoF (about 2.0). Other wheels have more but are not legal in FIRST because they destroy the carpet.

As to wheel size there are lots of pros and cons to each. Weight, speed, efficiency to name a few. It's really personal preference, do you need the weight? do you want low/high ground clearence?, ect.

As to whitepapers I think one team (234?) is working on testing various sized wheels for differences in preformance. However, I wouldn't expect it to be out any time soon.