Last year we ordered a new TT with an advertised dry tongue weight of 500 & something lbs. The CAT scale showed it was just under 1000 lbs actual weight all loaded up - approaching double. I ordered a new Reese WDH in advance with 800 lb bars.
With 800 lb bars, the handling was not good and the rear of the TT had a lot of bounce. At the scale, I could not adjust the WDH to get anywhere near enough weight transferred to the steer axle and TT axles(3/4 ton truck). Then I bought 1200 lb bars and after setting it up, it worked great and there was reduced bounce at the rear of the TT too. Our tongue weight ended up being about 14.5% of the TT gross weight and the gross weight was only a couple of hundred lbs below the GVWR (with 4 empty tanks too). It seems like TTs from some manufacturers can be a lot heavier than expected and you can end up with under-sized bars if purchased in advance.
Is there a difference in deciding on required spring bar rating versus a 1/2, 3/4 or 1 ton TV? Isn't it going to take more force to compress the front springs on a heavier rated TV?