Any ideas! I have a Toro proline 44" walk behind and for some reason I can not keep air in the right front semi-pneumatic caster wheel. I can not find any holes in the tire (after pumping it up I submerged the wheel looking for bubbles). That leaves me with a problem with the bead. I have inflated it to the max (50 psi) and still after a couple of hours the tire is soft again. This even happens when I fill the tire at night while it is on the trailer and then by morning it is soft again. Every dealer around here has gotten slammed hard and are backed way up. They all say drop it off and we will have it fixed in a couple days. Usually my dealer has me up and running again in a couple of hours. I can go one day but any more than that will put me way back. Anybody know how I can repair it myself. Thank you in advance.