I balanced my GMC's tires with BB's, as well as my trailer's tires. They ride better and smoother than the old ones that were on there.
Get a valve core stem remover tool and carefully take the core out. It'll unscrew like a normal bolt. This may or may not be enough room to get the BB's in there. It'll take a while, you'll need to put them in, one by single ****ing one. The heavier the BB, the less you'll have to do.
I used 9oz of BB's for a 265/75R16 tire and the 235/75R15 tires on my trailer, however, in all cases I had the tire broken off the bead.
If the BB's won't fit, get some play sand, heat it on the stove at low heat in a junkier pan to get the moisture out, and again measure out about 8-9oz on a scale. This will make it pour much easier too, and should accomplish much the same thing. Use a rolled up piece of paper with the end cut off as a funnel.