He saw 15 cars and 8 trucks so 15+8 = <<15+8=23>>23 vehicles
Those 23 vehicles have 4 wheels each so 23*4 = <<23*4=92>>92 wheels
Bicycles have 2 wheels each and he saw 3 bikes so 2*3 = <<2*3=6>>6 wheels
Tricycles have 3 wheels each and he saw 1 tricycle so 1*3 = <<1*3=3>>3 wheels
In total, Juan saw 92 + 6 + 3 = <<92+6+3=101>>101 wheels
#### 101