DOOR SLAMMER 4 Gear

Well, I'm not either one of those people... ;D.. But, I can answer you as to what my car was built like, and the tire size rule as I know it.
First, I do not believe there is a minimum or maximum tire size. So far, that has been left 'open', since this last DS race was the very first one and everyone was pretty much 'experimenting' with what does and doesn't work. The one thing to remember is that if you go too small, it may not (or may, I don't really know yet..lol) work as well because of that 'extra' gear in the 4 gear cars. They were designed with big tires to make up for that gear, and the Blue Drag arm that was in the originals, because that arm produces "high torque, but not as much top end". The principle to remember is just like in the real thing, which I raced for a few years back in the late '80's..."Larger diameter tires mean more rolling mass, which in turn means more top end speed".
That's how I figured on my DS car. I ran the stock AW rims. slightly narrowed by sanding the back side of them so they fit in the wheelwells of the body without touching the track rails, trued the rim with an emery board, and used silicone slip ons I got from Buds HO Cars. I silicone glued them to the rims. And, all the pics you see of my car is exactly as it was raced.
Like I said, I don't know if smaller ones work or not. I don't have a 'test' track here yet, as I have not gotten around to cleaning the extra room out to put it up. I REALLY wanna try making some of my own silly foams here, I did buy 20 pairs of the unmounted sponge donuts a while back to try it, but just have had NO time to do it.
Yep, we sure could use some REALLY nice 'custom' rims and tire sets for these! Everybody using those Slotted Mags that come on them is starting to look like all those sci fi stories of the past. You know, the ones where everyone dives the same color and make of car, all dressed the same, etc. That's why I used the wheel inserts from Tony over in the U.K. But, those might get expensive if you use them on ALL your cars...LOL! And, while rims from diecast cars might look nice, the problems there are that they do not have even ONE flange on the back side, let alone a 'double flange', and they are really hard to drill to fit the axles, and they almost always come out with a wobble. I have managed to find about 10 sets of diecast wheels that can be sanded down to glue silicones on, but as I said, all of them are wobblers. So, really would hurt a 'fast' car.
Joe, if you read the article in the new NTRA newsletter (just came out today) about making your own sily foams, it might be something you could try. If you want to try it yourself, send me a pm. I can give ya something that may help.
Hope I helped a little.
Ron (Bondo)