Replacement tyres and jockey wheel for car and cattle trailers simply replace the old wheel of your jockey wheel with the twin tires by removing the old wheel and fixing the two new wheels to the support using the supplied axle due to the new larger air tyres they have a higher footprint and thus an improved stability a further effect is an improved rolling ability over obstacles due to the larger wheel circumference when maneuvering the trailer by hand compiled for you in the set 1 tra