"MUD" gets in everywhere. Between rim and tyre, then you have a slow puncture that no tyre repair kit can fix. What do you do? Hi-lift jack to the rescue!
If you have a bead breaker it makes it very easy. If not, just position your hi-lift jack next to the rim as in picture and jack 4x4 up using the weight of the vehicle to de bead the tyre.
Unseat the tyre by using a tyre lever, or going around with the foot of the Hi-lift jack, then clean the mud out.