Our field gets pretty long at times too. I have experimented with different sizes and found that the best is 3" tires for the mains. The steering wheel on some of the trike planes is 1/4" smaller than the mains. In that case use 3" for the mains and 2 3/4" for the front wheel. I have tried up to 3 1/2" tires but the larger size can cause you other problems. BTW, buy Light weight tires instead of low bounce. 3 of these are lighter than 1 low bounce so you will save quite a bit of weight. If the plane is a sport model or a war bird then I like to use the fancier looking diamond treaded tires. Hope this helps. Fast!