R4s typically cost more. If you build your tractor on one of the several brand sites, they charge more for R4s. Since most dealers order their tractors with R4s, they price them that way. Some dealers are more honest with their pricing than others, and will discount the tractor if you get R1s, or at least explain the pricing difference. But keep in mind, if a dealer has R4s on the tractor you want, and has to order in R1s and swap them out, it's costing him more to get you a cheaper tire/wheel combo.