If you can buy another set of rims, you can then get the diameter measurement of your R4 tire, and then go to the tire web pages and get a 6 or 8 ply truck tire, with smooth tread tha will fit your 16.5 rim. You could also go to some of the tractor part sellers and possibly find a rim that will bolt up to your bolt pattern, even in 15" or 16" size, select your width, and then once again go to the tire web sites and find a tire your like in 6 or 8 ply. You need to becareful about the rim offset for the front wheels to clear when steering. If you can live with out 4WD for mowing, then stop worrying about wheel diameter, just leave it in 2WD. Even with the front over driven about 2% in 4WD, a smooth, slightly smaller in diameter front tire won't hurt your drive trian. It will either be almost matched to the ratio for 4WD, or will slip enough on the grass not to "wind up" the drive train. /forums/images/graemlins/grin.gif