244 / 40 20 would be about 1/5 inch skinnier and around .7 inch taller I wouldn't that would be even close to enough difference to cause any problems with the nanny's and the speedometer runs of the front so you speed should still shoe correctly
as a side note I dont see any reason why your rear tire has to match the fronts
I agree that the front and rear needn't be the same tire, in fact, we are still running our BFGoodrich g-force Comp-2 tire on the rear with the new Yokohama's on the front. I am thinking that we are so pleased with the performance of the Yokohama's that we want to install on the rear also when the time comes.
As another side note, the one time I had the thrill of doing the do-si-do down the interstate after a hydroplaning incident, I am not sure which lost traction first, the front or the rear? We had the original Kenda's installed at the time.
Bill