Multiple plots

[alcesgabbo]

I have a variable :
sim.var[,1]

Object of class SpatialPixelsDataFrame
Object of class SpatialPixels
Grid topology:
     cellcentre.offset cellsize cells.dim
Xloc               0.3     0.05        97
Yloc               0.1     0.05       117
SpatialPoints:
        Xloc Yloc
   [1,] 0.30 1.70
   [2,] 0.35 1.70
   [3,] 0.35 1.75
   [4,] 0.40 1.70
   [5,] 0.40 1.75
   [6,] 0.40 1.80
   [7,] 0.40 1.85
   [8,] 0.40 1.90
   [9,] 0.40 2.10
  [10,] 0.40 2.15
  [11,] 0.40 2.20
  [12,] 0.40 2.40
  [13,] 0.40 2.45


and a variable :
sim.mean[,1]
Object of class SpatialPixelsDataFrame
Object of class SpatialPixels
Grid topology:
     cellcentre.offset cellsize cells.dim
Xloc               0.3     0.05        97
Yloc               0.1     0.05       117
SpatialPoints:
        Xloc Yloc
   [1,] 0.30 1.70
   [2,] 0.35 1.70
   [3,] 0.35 1.75
   [4,] 0.40 1.70
   [5,] 0.40 1.75
   [6,] 0.40 1.80
   [7,] 0.40 1.85
   [8,] 0.40 1.90
   [9,] 0.40 2.10
  [10,] 0.40 2.15
  [11,] 0.40 2.20

If I plot these variables with:
spplot(sim.var[,1],main="var")
and
spplot(sim.mean[,1],main="mean")

it works.

But how can I plot these two variables together with a single scale?

Thanks