i wouldn't do that if urs is 4wd because you front axle is always turning the tc even in two wheel drive it just doesn't get power. just get a roof rack and put it up there
Just thinking.. could i run a smaller spare? Provided i only run it up front and only in 2WD, shouldn't hurt anything?
Yes you can, but if you have access to a full size spare I'd go that route. 2wd xjs actually came with "donut" spares. Of course, too much difference in size would quickly lead to you driving off the road.