Why Mitsubishi do not want to offer a skinny spare to get to a tyre dealer is beyond me, as other car manufacturers , although they offer an inflation kit, also offer spare wheels. I realize this is all down to costs since if you multiply the number of cars produced by the cost of a spare, whether steel or other, the money saved is colossal. Now if you want to carry a spare, whether the cost or weight is acceptable, should be down to you & the manufacturer should offer something. As long as the rolling circumference is the same for all tyres, there should not be a problem although I do recall that Range Rover had a problem years back when a spare was used, messed up the fourwheel drive setup.
I would like to buy Dynomec spare wheel , with the right sized tyre but how the dealer would accept any problems that later happened could be costly.
MikeI GX5hs