Rubber tracks will be to rubber tires what rubber tires were to steel wheels 60 years ago, according to experts who have watched the huge success of Caterpillar's Challenger over the past few years. Now a European manufacturer has come out with what it says will be the first affordable rubber-tracked tractor for the average-size farmer.

ZTS Martin is a subsidiary of the Czechoslovakian tractor manufacturer Zetor, which has made strong inroads into the U.S. market over the last few years. ZTS designed its new PPT 130 tracked tractor to compete with the Challenger and also with the Track Marshall (built in England) but it plans to knock 30 percent or more off the price. So far the tractor is only available in Europe.

Features a 6-cyl. Zetor engine delivering 175 hp with hydrostatic steering operated by a wheel (rather than levers) like the Cat Challenger. It has a conventional synchromesh transmission with 32 speeds forward and 16 reverse but the company plans to offer a hydrostatic transmission.

Unlike the Challenger and Track Marshall tractors, the Zetor has both front and rear 3-pt. Its tracks are made of rubber-coated steel plates that allow road speeds up to 15 mph. The large rear drive gears provide the power.