Originally Posted by cuffydog
I'd like them to be both durable and light. I looked at the Schwalbe marathon plus tires If26.1.3) but wondered how they'd do on dirt.
"durable and light" are usually mutually exclusive in bicycle tires.
None of the Schwable "marathon" series of tires are light, but they are widely praised for durability. Even their 1.35" Marathon Plus is not light (listed at 830g), for a 26x1.35 tire. Their 26x1.5 Racer is not so heavy, but at 100 USD a pair they are expensive. You can find other maker's tires in this size and weight for less than half the price.
26x1.5" tires will roll fine on hardpack dirt roads/trails, but if there's any sand or much gravel you're better off with a wider tire, like a 26x2.0. There's a few 1.7-1.75" tires available too.
If you live close enough to the pavement where you can walk over the rough sections of dirt, then perhaps you could run some 26x1.25 tires, which are usually light (~200-250g), and not hard to find at a good price. Performance Forte, for example.
I personally use 1.4-1.5" tires - I find they're a good compromise of durablilty, weight, comfort and cost. If you go below this, tire makers tend to compromise durability (thin tread) to achieve a low weight (key selling point). I wore through a Hutchinson 26x1.0 in 350 miles. Just once.