sb53

i have done some calculations (hope they are correct) the existing tyres 245/40, now i think the 40 is a % of 245 and is the distance from the rim to the top of the tyre - so 245X .4 = 98mm(x2) +19inches (482.6) 98mm x 2 + 482 =678mm, the 18 inch spare is 135/80 - 135 x .8 = 108 (x2) - 18 inch wheel is 457, so 457 + 216 = 673.
so only 5mm difference.

bought an 18 inch recovery wheel (red - i am informed the black ones do not fit) and it fits a treat. Also bought the circular tool kit and that fits with the cover going flush as it should do. Note a full size wheel would not fit.

As an aside i changed the battery - note  the negative battery lead must lie flush with the battery otherwise the battery fixing bolt will not line up. Bought a ICarsoft code machine as you have to tell the computer that it has had a new battery (apparently it reduces the charging rate which then increases as the battery gets older. 

not a cheap solution but now i have a real tyre and not a can of gunk!

my jag XF has 245/40Z R19 98Y tyres on it. The car has the tyre glue and i want to relace this with a space saver. 19 inch used space savers are rare and expensive - can i use an 18inch space saver given it is only a temporary fix
thanks