[folivier]

I had a similar issue with my '93 and like Michael I spoke with the head of engineering (who is now retired). He said that mine along with others of that genre were rated based on the tires available at that time and that the coach was able to handle the weight. He sent me a new vin tag with the higher ratings based on H rated tires available today. That solved my overweight issues.
Might be worth a call to Newell.