I vote for more torque and 152 or 200 rpm. That still gives an overhead for pwm to get slower. Just my opinion. Edit. I just looked at the link you had. I didnt realize the speed was already in there with the wheel size. Unless Im missing something Im coming up with over 32K mm per second. 68mm tire size X 3.14 X 152 rpm = 32455mm per sec or 1277.7559 inches per sec or 106.48 feet per sec. Im a bit tired it seems. EDIT: I slipped up and didnt realize I forgot the answer was per minute not per sec.

I checked the math Troy. The wheel diameter was 65mm. That translated to 2.559 inches, giving a circumference of about 8 inches. Turning at 152 rpm would be 1216 inches per minute, or about 20 inches per second. It would cross a good size room in about 10 to 12 seconds.

So we have it! Ill get the 200rpm motors

Got my ping sensors from china last night and inspected them. Some for roli mega, the others for my next bot.(trying hard not to spoil the surprise!)

Thought i'd post product info for anyone who finds this thread. Product Name: Mini DC Tyre Motor Assembly; Motor Model: 37GARH; Voltage:12VDC; Rated current: 1.1A; Motor No load speed: 200r/min; Motor rated speed: 152r/min; Motor rated torque: 2.8kg.cm; Tyre: 6827mm(DT); Shaft:Dia 37mm Long; Motor Speed: 653.14152mm/s; driving force: 2.8÷3.25kg Total Size: 65104mm(DH); Material: Metal, rubber; Color: As picture shows; Weight: g; Package Content: 1 X DC Gear Motor + 1 X coupling + 1 X stand + 1X tire;"

www.ebay.ca/itm/12V-200r-min-Playmobile-Assembling-Tire-Drive-With-37GARH-DC-Electromotor-/161096790486?pt=LH_DefaultDomain_0&hash=item25821df1d6

@danger, thx, lol I knew that I couldnt be right on that math.

No problem. The first time I did it, I was thinking it was 20 feet per second. I told techno that it would be way too fast. Then I thought about it and had to go back and edit my post. 20 Inches per second is still a little quick for a robot but I am sure that with pwm he can get it into the right ballpark.