I have no complaints about the factory Westlakes either. A few thoughts however:
If you're jumping up from D to E, you might also have to bump up a size as well. Do you have the room between the tires to run a bigger size? Also, "E's" run at 80 PSI. Are your rims up to the higher pressure? If it's a stock Forest River rim, it should be, as I remember one of the factory guys saying in one of the tire threads from way back that they use the same PSI-rated rims on everything. But still worth checking.
If you want to jump from "ST" to "LT," again probably a size change. You gain speed rating with LT tires but lose load rating. It's up to you what's important to you.
But I agree with the previous posts--scrap that tire yesterday.
2015 XLR Hyperlite 30HFS5 (mods being performed regularly)
2009 Salem LA 292fkds (gone)
Nights- ('12)23 ('13)23 ('14)15 ('15)31 ('16)25
2014 Harley Davidson FLHX (XLR cargo)
2014 VW Jetta TDI (diesel sipper, camping support vehicle)
2011 Ram 2500 CC 4X4 CTD, B&W Companion (toy hauler hauler)