Yes, surely they're taking about SORCCA comp rules. They're posted somewhere here - let us know if you can't find them. And the score sheets for scale points. It's kind of like golf scoring, or observed trials - less is more. ;-)
You should have asked - they wouldn't have minded explaining it to you. Crawler guys are a helpful and friendly bunch.
To add to SVT's post...tire size is a biggie, as well as other 'scale' requirements of the classes:
Class 1 - Street/stock looking vehicles - This is more or less the 'scaler class', tire size limit to 4.19" diameter. Fenders must cover at least half of the width of the tread. Full width bumpers, points for hardbodies, operating functions, metal bumpers and sliders, lighting, etc. C1 C2 require a steel c-channel frame.
Class 2 - Modified vehicles for off road, mostly still street legal - This is actually a pretty stock class as well, with similar specs to C1 but tire size limit to 4.75". Some call this the 'box stock' class - for new people with new rigs right out of the box.
Class 2.5 Some clubs have this class which is C2 but for modified rigs. It's an effort to keep them competitive and not lumping the highly mod'd rigs with the noobs.
Class 3 - Vehicles built for off road, not street legal - This is more or less an open class, 2.2 wheel size, buggies, cages, boat tails, bobs, etc.
The best way to learn is to simply go and participate. They're a lot of fun and you learn a lot about rig setup and driving. I've seen routes and gates and lines I would have bet were impossible to drive - only to see a rig drive them. And then drive them myself. There's a lot of skill and technique that goes into it all. Just enough complicated to be entertaining. "thumbsup"
