So I'm making this car. Everything works fine, except for the back wheels. Whenever a Sims drives a car, the back wheels spin around in the air, like so:



So I figure it's to do with the bone assignments, but I have checked those now for like four times already. The bone assignments are correct.
The only problem I can see is that this car isn't as long as the original cloned car, which means the wheels are not in the same place as the original wheels. But should this pose a problem?
Thanks for helping!

So I figured it out... my theory of the original placement of the wheels was correct: because the back wheels aren't in the same location as the reference mesh's wheels, the bones rotate them incorrectly.

Did you figure out how to fix the problem, or did you have to give up on the project? I tried to make a Penny Farthing bicycle (cloning the base game bicycle) but had the same problem as you - the bike looked great parked, but when the sim rode it, the miniaturised back wheel spun around in mid-air behind the bike. If you managed to fix the problem, I'd be very grateful to know what you did!

Nope, I've had no luck so far. It's really frustrating, I've spent close to ten hours now trying out different methods. Even editing the RIG resource, moving around the actual bones. But no go, the wheel keeps spinning mad like that.

I kind of have a stupid suggestion - no idea if it'd make sense but... can you just attach the back wheels to the car itself? As in, make them part of the body of the car, so that they will not rotate at all. The cars in TS3 are kinda crappy for animating anyway, and wheels going just the right speed IRL may appear to be standing still, so it probably wouldn't look too bad and would probably be easier than beating your head against a 10 hour brick wall.

As long as there is no way to edit the RIG resource there will be no way to make cars or other vehicles that have non standard wheels or positions of wheels (compared with the cloned base object). Yes, it's frustrating. I'd liked to convert some of my Sims2 vehicles to Sims3 but no chance till now. It also might be necessary to change some values in the animation resources but I'm not sure. You also will have a problem with the position of passengers. Changes of slot values will lead to a loss of animations or the sim even will not be snapped into the slot, but will be teleported to the destination when the vehicle is moved. This was my observation trying to make several changes.
hexameter
Edit: Great idea, HP, at least a good compromise!

HP, that could be a great idea - when I made my Penny Farthing, another unexpected problem was that the spokes on the wheels no longer spun anyway, and I thought that in itself would be considered unacceptable for upload. If non-spinning wheels are acceptable, maybe I'll have another go at my PF by making the rear wheel a part of the bike body as you suggested.

There is a small car available for download from the EA Store which should similar in size to the Smart Car:

Renault Twizy Z.E - http://gb.store.thesims3.com/renault.html

Hexameter: that's what I've been doing for the past ten hours, trying out all different values in the RIG resource using ChaosMage's Rig editor. I calculated the offset between the two rear wheels and the original bones and edited those values in the Rig resource. But no go, it keeps doing weird stuff.

HP: that's a great compromise, actually. And after ten hours of headbanging and having not enough sleep, it's one I'm willing to make.

Ceixari: that's right, I had forgotten about that car! I'm gonna try experimenting with that.

Try the latest version of TSRW
Its awsome for creating cars

That's what I tried, too, after many tries during the last months using the other tools available including a hex-editor. The results I described in the former comment. Concerning the RIG Editor I think, as far as I understood the discussion, it has to be improved in some aspects to do its job.
hexameter