Originally Posted by Kro1957
I have a newer Reese 15K slider. But recently upgraded RV and going to a 18 or 20k Reese. Would I have to change out rails also?
No. What Ray said. All the normal Reese 5er hitches use the same install kit (bed rails), Reese part number 30035. From the el cheapo Pro Series 15K to the 22K, and including the newest R20k that meets the new SAE J2638 requirements. Reese doesn't make an 18K "normal" 5er hitch. Their 18K 5er hitch is for the Ford factory prep kit or the Reese Elite install kit, which use under-bed rails and will not work with the above-bed rails.
Reese makes at least three different 20k hitches that all use the same #30035 rail kit. The el cheapo ProSeries, the old standard Reese 20K 4-way tilt 5er hitch, sometimes called the Classic or Select Series, and the new R20. Ignore the Pro Series and get the old classic or the new R-20.
Reese Reese R20 5th Wheel Hitch 30867
RV dry is like 14.7k so I would be pushing the upper limits of that 15k, even if it was just to take it 250 miles at it's summer home.
Dry weight is a useless spec. Go by the GVWR of the trailer. You probably need a least the 20K. If the GVWR of the trailer is more than 20K, then I would move up to the 22K Select Series, which also uses the same #30035 bed rails.
Reese Select Series 22K 5th Wheel Hitch
If you need more than 22K, then Reese doesn't make one that will use the "industry standard" bed rails. Their 25K is for the Elite under-bed rails, and their 30K reqires 1/2" steel plate that attaches directly to the frame without using rails.