We have run the JD no till drills since 94 and also had our share of bearing trouble. The JD seed firming wheels had little bearing trouble,usually lasting 3-4 years. we replaced them with the narrow (5/8 inch wide) SDX firming wheels which pack the bottom of the seed slot better than the 1 inch wide JD wheels. We have run the SDX wheels 3 seasons now and not had a failure. Those tough plastic SDX firming wheels are very durable in rocky conditions. We would break a few of the aluminum JD wheels every year.
The JD closer wheels have always had bearing problems because the sealed side of the wheel is exposed to so much dirt, and the bearings are small and poorly sealed. They have changed the seal/ and bearing design at least 3 times,but still have problems. The newest ones with the bearing in the arm instead of the wheel are better.
We replaced our JD closer wheels with after market Thomson spiked closer wheels sold by Exapta solutions,these have not had any wear or bearing problems in 3 seasons. we would not go back to to the stock wheels,as the Thompson's do a really good job of crumbling the seed slot closed and no more bearing and seal troubles. The Thompson wheels use a common single large bearing available from any bearing jobber or JD. I don't know where JD uses that bearing,but they should fit it to their closer wheels,or better yet,Thompson wheels should be original equipment on the JD drills. We tried a couple of IH guage wheel tires on the Deere drill, but have not noticed any advantage to using them. Too much down pressure is a guage wheel killer.
Our soil is heavy clay/loam that has not seen a tillage tool since 94.
