M/T Drag radials -- What air psi for the street?

Recently bought some new m/t drag radials 275/50/15. I plan to use them on the street once in a great while. What air pressure should I run into them for the streets - that will still give me excellent traction.

I run the M/T Radial 255 50 R16s at no more than 25 psi on the street. Too much air and the centers wear out real fast. If you're not sure, then air them up and draw some chaulk across the tread and get chaulk to wear evenly. They are the only tire I run and they've got 30 or so passes and 1500 miles and they still look great...They seem to wear better than my BFG DRs ever did...

--Alan