anyone know where to get four-inch pneumatic wheels?

[pipsqueaker]

^

So far our team has only been able to find 6-inch wheels

[sysdes]

The smallest I have come across are 5 inch. Typically used on rollerskis. Check out www.nordicskater.com.

[CalTran]

Any particular reason your team wants specifically pneumatic wheels as opposed to HiGrip/Peformance/Colson wheels?

[Knufire]

I remember spending a significant amount of time looking in 2012; smallest I ever found was 5".

[Peyton Yeung]

Likewise I spent many a night in 2013 looking for a 4" pneumatic wheel with no such luck.

[asid61]

If it's for drive, plenty of other options.
If it's for intake, colson wheels have unbelievable grip.

[ToddF]

Google is your friend.

http://shop.dubro.com/p/4-dia-big-wheels-2/aircraft_tires-wheels?pp=12

http://shop.dubro.com/p/4-dia-large-scale-treaded-wheel/aircraft_tires-wheels?pp=12

http://www.gmade.net/bbs/zboard.php?id=wheels