From my research, I found that your Itasca Ellipse is just shy of 43 ft long.
The only option we currently offer for RV's that are 34 ft or longer is the Ultra-Fab Skid Wheels for Class A RVs 34' and longer - 6 inch Diameter, part number # UF48-979013. However, none of our skid wheels (including these ones) are recommended for use on diesel pusher motorhomes due to the extreme rear-end weight of the motorhome, which would shorten their lifespan. The replacement casters are available separately... view full answer...