Steel rims responsible for slicing tubes? I have an old Giant dutch bike and it has steel rims. Since I'm a big boy I felt that the 60PSI on the tyres is not enough and pumped my tyres to the maximum of 85PSI which is what my Schwalbe Marathon Plus tyres were supposed to be able to take in. It was great, riding was so much easier all of a sudden! Not the slowest guy on the road anymore, really fast if I wanted to in fact! I loved it.

Unfortunately a few days after I came to find one of the tubes neatly sliced. The tyre untouched. I wasn't sure what had happened but walked to work that day and planned to bring it to the workshop asap. When the day came I exited my house and found the other tube sliced in the exact same way.



I have meanwhile talked to lots of people. Some say it has to do with the steel rims even though I can't make any sense of that. I have also encountered people that said I just need the right tubes and tyres and it shouldn't happen anymore.

I'm now thinking of either buying a new bike, exchanging the wheels(which would be more expensive than the initial price tag of the bike) or give new tubes/new rimband and maybe different tyres a shot?

Does anyone have experience with this sort of thing or any sort of input?

this didn't help: Tire popping out of rim when inflating tube
OK if the tire was blown off the rim then I highly suspect that is the whole story.
When the tube leaks out the because tire bead has come out the tube will burst and you will see a slit.   

A tube outside a tire cannot take much pressure.  

Most likely when you went from 60 to 85 psi it was enough pressure to push the tire off the rim (bead).  

I have seen this with some older bikes.  The rim is a little small.
Look for tires that run small and run at lower pressures.  

You might also have a mismatch like a 27 on a 700c.

A Schwalbe Marathon Plus is a pretty hefty tire and tend to fit a little tight so this is kind of strange.  But it did happen after you went to 85 PSI. 
Maybe give it a try again at 60 PSI. Even if you get a new bike you would have this as a backup.