My Trek 7.4 has Bontrager Nebula rims and try as I might I can't find any information as to how much they weigh. Do any of you have any suggestions?

FYI - I am wanting to do some Gravel riding and want to use 38 mm tire rather than my 28 mm tires so, I was thinking of new wheelset the issue is whether to put the 38 tires and the 28's on another lighter wheelset. Any suggestions?