what did you insert in your crawler tires?...I just thinking of adding some small heavy balls, like the ones in Ball-bearings, for adding heavy (and grip) on the front tires...did you use some on the back one too?

PS. I use a G-made SPIDER

I used stick on lead weights used for full size cars. I've only used them on the front. Some people do both front and rear. Another alternative is BBs used in a pellet gun.

nice setup....but I was thinking of small balls because spreading inside the tire, will give some much terrain grip...moulding the surface...(my english is not so good[:@])