I have a set of new 235/75/15 bfg knock offs. I have a 2001 Grand Vitara stock with 16" pretty chrome wheels and bald stock tires. I have a stock pile of stock samurai 15" 5 on 5.5" rims. What's the chances I can make this combo work with maybe wheelspacer? This vehicle is used mainly for street.

I have a 2003 Tracker, so its not exactly the same, but I have read on this forum that you may run into problems. Your wheel and tire size will match up fine (I am infact running 235-75-15's on 15" x 5.5" wide factory steel wheels). There will be some body/frame rubbing, but you can cross that bridge when you come to it. The spacers will solve most of those issues.

The problem I have heard is that the Grand Vitara has bigger brakes (calipers) which will not allow the 15" wheels to be installed. If you have them lying around, just pull the wheel off your truck, and try to bolt on one of those 15" wheels. If it fits, you may be in luck.

Like I said, by Tracker is a more stripped down version of the Grand Vitara (no V6, and I believe smaller brakes). This is why the 15" wheels fit some and not other GV's and Trackers. Give it a try, and let me / the form know.

I think Kink is on it with his answer.  The beefy calipers on the GV may be the show stopper for your tire/rim combo.  I agree with his solution too.  Slap a 15" steel wheel on the puppy and see what happens!  Maybe you can trade up tire rim size and you'll be good to go.  I have a tracker with 235/75/15s on it too.  They did rub a small area on the frame at full lock-up.  I haven't noticed this anymore with a 2" lift on the springs.  235's aren't really that large of a tire.  They're only "large" compared to the Tracker OEM tires of 205/75/15s.  But I'm good with 235s for what I use Buster for.