That is a tall tire and will set his speedo off by at least 5 mph, and I'm not sure but there may be a problem with the ABS as well. Are they 9's? then he would be better off with a 275/40 which is almost exactly the same as stock height, no speedo error. 255/45 on an 8 wouldn't be bad either with less than 1 mph difference. Some guys run 275's on 8's, but they might bulge a bit and wouldn't be ideal for handling.