BFGs..? Not in the rain.
I drive 50 miles each way to the track, and they're fine. But judging by how easy they spin after being in the track's almost dry water box, you definitely would want to check on the weather for the day.
Just like being on ice once you get them wet at all.
On the other hand, if you have an RT/10, they'll fit in the trunk upright, and you can drive on your street tires. They fit in the trunk of my '94 nicely. Put a couple old towels over the tops of the tires so they don't mar the inside of the trunk lid, and bungee or tie-down the lid just a little bit. They aren't going anywhere.
In fact I had some real monsters mounted on my 17" rims for a few weeks, off of some Indy car or something. Those fit in the trunk standing up as well.
