In Lightwave the measurements for a "block" in Stadium is 32m x 32m x 8m (same as the regular square circuit block). This will turn up in 3dsmax as the right size if you export to .3DS from LW with all export options unchecked (rotate, scale etc). And remember to rotate it forward 90 degrees around origin and triple it first (when looking at it in the "right" viewport, rotate towards the left).
Any Lightwave user MUST first import the model (including vehicles) into 3dsmax or blender to set the properties & UVW. Even if you find an FBX export plugin for LW it won't work. Yes it sucks to have to learn another 3d prog just for this, but it isn't really that complicated since you already use another 3d prog. Plus there are tons of good tuts on youtube

Just as a little sidenote (after you have watched it): you don't have to collapse the modifiers. Personally I made one UVW and then copied and pasted it and just set the new one to mapchannel 2, then name the mapchannels "Material" and "Lightmap" as usual. It seems to work just fine.
Not sure if it's mentioned anywhere, but the size of a standard "block" gridposition in Stadium is 32x32 width and depth (and the height is usually 8).
In the xml, the units(steps) for the aforementioned stadium circuit block would be 32x8x32. So meters in LW = xml value.
If you made a circuit block just like that, the xml could e.g. read:
<Object>
<GridSnap HStep="32" VStep="8" HOffset="16" VOffset="0"/>
</Object>
Where Hstep is horizontal steps. 32 being the whole length of this object, so it can't overlap in the editor and fit together perfectly. Same with VStep: vertical steps, in this case 8 which is the exact height of this object. In this case however, the pivot is right smack in the middle so the object grid doesn't fit with the default grid. if u lined it up with blocks that comes with the game u would get something like _-_-_-_-_- meaning u gotta push it half the object length to make it line up. Which is why the HOffset is set to 16, making it more like ======.
The pivot settings are more hazy to me still, but I know you can change the pivot position for the object. Perhaps that's all they do? I checked the files in the "Dolmen" example, but I got no idea why there are multiple pivot entries in one xml. I also figured out that the middle value of the three is the vertical axis(Z). It's possible I could drop the HOffset and just move the pivot, but it works fine for now. I also still don't know how to make it move upwards without something under to support it. But then again...this is all still beta

Good luck LW people

PS: Anyone know how to get a dirt piece from stadium? Being a dirt racer I wanna make dirt bits, but since the ground in a dirt-road bit is curved it's impossible to make it fit other dirt bits without having a template first.