[CALinSC]

I'm thinking your trailer has 7000# vehicle certified GAWRs. With your current tire size, you're not getting much in load capacity reserves from them at 80 PSI.

The considerations for adding load capacity with your replacements include replacing all valve stems with steel ones. Do you have an air compressor that will easily provide 95 - 110 PSI? With a 2009 model year your wheels may be rated for 3640# of load capacity at 80 PSI. You will need wheels rated higher than 3640 to take advantage on the load capacity reserves LRF or LRG tires will provide.

I'm not a brand pusher. There are more than a dozen tire manufacturers building steel cased ST235/85R16 LRG tires. IMO getting them from a local retailer is the best way to go.

If you're not going to do some traveling outside of your state I'd stick with the vehicle certified OE tire size.