Hi tire newb here. My DR350 was running a Kenda K270 in 4.5x18", by mistake I ordered a replacement in 4.6x18". It sure looked skinny compared to the 4.5 (4.3" wide versus 4.8"), it was only 4 ply and had a load rating of 600lbs versus 800lbs for the 4.5. The 4.6 seemed to perform well as I got near 5000 miles out of it and completed the Washington Backroads Discovery Route on that skinny rear tire. My store does not have any 4.5 or 4.6 left in stock so I was looking at the 4.00x18" and noticed it was cheaper, had 6 plies, was the same width as the 4.6, has a 700lb load rating and is and its OD is in between the 4.5 and 4.6. Is there any reason I should not go with the 4.00 for my DR350 rear replacement? Thanks!