Bicycle Tutor

I ordered, from a bike-shop, 3 tubes for my kojak tires. Instead of the good size (20-40mm), they send me a bigger size (40-60mm). I wanna know is it safe and if it's ok to mount my kojak (26"x1.35) with this tubes.
thanks a lot!

Should be fine, but it depends on if you can get the tube into the tire without any twists or bends. Tire sizes are notoriously inaccurate, so it's hard to say firmly yes or no. Try inflating a tube just enough so it starts to take on it's 'donut' shape. Then see if you can fit it in the tire without any major kinks. If not, return the tubes. If you install a tube in a tire with a fold or bend in it, you do risk the tube pushing the tire off the rim and giving you a flat.