I have a 89 blazer with a 4" lift & I'm going with bfgoodridge mud. Would it be better to go 33's or 35x12.50x15??

 

I think your axles, assuming they are stock, will like the 33's much better than the 35's.

 

yea ajbert is right you don't want to get much higher than 33's unless it is strictly a road queen