I had a set of 38 12.50 TSL's on my '83 long box and a set of 38.5 14.50 SX's on an '89 ex-cab. Both DD's and they both were about the same on road. The sx's rode a little better on cold mornings,but they seamed to wear faster. I had them both on ten wides and the 12.50's were pizza cutters compared to the SX's. A lot lighter too. I bet a 39' irok would be right between the 2 in weight.
