Well, It's always what you do out of a game. That's why I don't understand all those cry babies (I don't mean you)
If the AI isn't challenging, make them challenging! But Just put one or two tireclasses below the allowed ones and also don't use the maximum LP as possible. Also keep in mind that the AI are driving stock cars. So do you really expect they are challenging when you enter the 550lp race with a max tuned 550lp car with race brakes and stuff?
I always entered the races with cars below the allowed LP-limit with worse tires and I had great fun and battles.
I really don't understand why everybody is moaning. The LP Limit and tire choice is so high so that even bad drivers have the possibility to win. You don't need to exploit it..