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I would like to build the three types of JPL Mars rovers (Sojourner, MER and MSL) with the right size ratio relative to each other. For that, finding the right wheels would be the hardest thing. I can build the rest of the robots as long as I know the wheels will have the right look.

Here's a pictures of the three wheel types:

enter image description here

enter image description here

Important Notes:

  • The overall size doesn't have to be at the scale of the minifigures. Even though this would be really cool, it would turn the Sojourner project into a micro build. This would be much harder.
  • The look of the wheel hubs is not relevant. What is important is the look/ratio of the tire's outside dimensions. Note that Sojourner's wheel (the small one) has a flat rolling surface while the others two are rounded.

Edit: The medium wheel is (appropriately) 1.8x the size of the small wheel while the big wheel is (appropriately) 1.7x the size of the medium wheel.

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4 Answers 4

It would probably be easiest to work out the which piece should be used for the biggest wheel.

The largest wheel I could find came in the 8420 Technic model. Two of which can be used in tandem to increase the surface area of the wheel:

Wheel Technic Street Bike (8420)

enter image description here

The medium wheel could be a rather blocky Wheel 20 x 30 Technic, the 68.8 x 24 or the incredibly useful 30.4mm D. x 20mm (four of which come with the NXT 2.0.)

The smallest wheel can be any of the tyres from a medium sized LEGO CITY vehicle such as the Prisoner Transport set.

I'd recommend having a look at Bricklinks database of wheel pieces to see what else is on offer.

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Thanks for the links. I'll dig around on Brinklink to see if I can find the right combination of sizes(ratio) and of looks. I'm also interested in the full wheel-tire BTW (not only the wheels). –  pcantin Jan 15 '12 at 1:14

The first that came to my mind (for the MER-wheels) is the Wheel 70 x 28 mm Futuristic, with Black Tire:

Wheel 70 x 28 mm Futuristic, with Black Tire

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You might also be able to make wheels out of parts, such as a circle of hinges with brackets and cheese slopes. I'm sure there are better ways, but that was the first that came to mind.

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2  
This reminded me of an old BrickVista post where that guy build a Sojourner wheel out of Technic pieces brickvista.com/features/roverWheels/roverWheelsHome.html –  pcantin Jan 17 '12 at 13:08
up vote 5 down vote accepted

Here's what found after playing with all kinds of combinations. With this the three rovers will be at the same scale (about 1:5.8). This scale is small enough that the big rover (MSL) would not be a monster to build.

enter image description here

The ratio is almost spot on and the only main problem is that the MSL wheels (the big ones) will have those big cleats.

On the positive side, they all have the right shape. Only the medium wheels have that bulgy look while the other two have a flatter driving surface.

Here are the parts numbers:

  • Sojourner (small): 6014ac01
  • MER (medium): 6580c01
  • MSL (big): 64711
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1  
Well found and good luck with the build :) –  Zhaph - Ben Duguid Jun 17 '12 at 9:03
1  
I'm only missing 1 wheel (2x 64711) for the MSL rover so I'll order that online. It won't slow me down too much since I'll start with the small rover and build my way up. I'll probably document the build (or show the result) on my blog. –  pcantin Jun 17 '12 at 11:57

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