My 235/50/18 tires were also bald at 20K. If tire performance is not extremely important to you, perhaps you could consider a couple of Michelin tires. Michelin has a Energy Saver tire that gets pretty good reviews and supposedly saves on gas. 55K to 65K mileage anticipated. Probably will get less, but 40 to 50K sounds pretty good to me. Michelin also has a tire called Hydro Edge. Excels in wet weather, I'm not sure how it performs on dry pavement. The mileage is listed at 90K, which sounds great, but I live in Arizona, so probably not the tire for me.