Bobby Car Whisper Wheel Replacement Tire

The idea was to have two sets of tires and be able to switch between them for inside and outside use.

Obviously, the printed ones are for inside use, since the TPU isn’t super abrasion resistant and I didn’t want to use a lot of filament.

In the end, the car didn’t end up outside once (yet), but I wouldn’t want to switch the tires every time anyways. It is really a finger breaking task. Getting the originals off and on it’s easy enough, but the printed version ended up quite tight.

TWO IMPORTANT DISCLAIMERS:

1. These tires only fit the Whisper Wheel Rims! 
   I believe some Bobby Cars come with these equipped, but for the original red one, they were separate
2. These tires are not as quiet as the original Whisper Wheels!

Now for the story:

I didn’t think a lot about the tire tread, when designing the tire. The first version, the one that I printed, is a bit rumbly. Because there is no continuous contact with the ground in the treat, like with the original tire tread, the replacement definitely cannot be considered whispering anymore 😂 

The car is rumbling for good now. While driving, the car bumps a bit every time it falls into a pit in-between tread nobs. This emits an almost motor sound like noise and I can only assume that it must be sensible, when sitting on the ride. 🤷

Anyways, I don’t find that annoying when the car is being used and my kid seems to have fun, so what gives. But I don’t recommend to use these tires when you have people living below you, they will probably hate you for it!

Only after I had all four tires printed, I realize this specific flaw in the design. A quick fix was to  rotate both sides of the tread against each other by a couple of degrees. So just in theory this should be enough to make things smoother. But I didn’t bother printing a new set to try.

There are both versions available here, so decide for yourself, which one you like most. Just for reference, blue is bumpy and green is smooth.

Printing Instructions:

• The filament needs to be flexible, or you won’t get it onto the rim. Regular TPU (90 or 95) is good
• Print with 100% infill
• My TPUs stick to the bed like crazy, but if yours don’t, activate the inner brim 
• You could try scarf joints, because my regular joint did not turn out well and because of the thin material, it might tear at some point
• Since my tire sits on the rim very stiff, you could try printing in 101% or 102% (in all dimensions). Don’t go higher or the tire might begin to slip

The Onshape model is here: https://cad.onshape.com/documents/6d558c5fcf01d212b75ad190/w/cbfafb5b2c1d8379070cc5cc/e/02eabb4c4c43cf0344d3b807