Can I use a road skewer on a mtb rear wheel. I have damaged my existing mtb one and have a road one that is the same style, a shimano black lever but is a 130mm length not a 135mm. It still takes a good few turns to screw the other end in and feels solid. I have another mtb one but it’s a different make and I did try that in but it seemed very long and the axel came out of the other side through the plastic nut by about 5mm.

I’d go longer than shorter if I were you.

I’d want to check there’s enough thread engagement in the ‘nut’. If so then I’d go with it. How much is enough… not sure bit zi know I’d know when it wasn’t!

The other way, I used hope  mtb skewers ona Road bike for years without problem except the 5mm sticking out.

Road rim brake qr skewers are 130mm.

They aren’t. The spacing between drop outs is 130mm. The skewer has to be long enough for that plus the thickness of any dropoutx2. Drop outs vary, there is wiggle room. If you get a good few turns on the skere nut end than you are golden. I’d be more wary about what the skewer is but as its shimano…. crack on.

Not convinced you could do that using a 130mm on a standard axle disc Mtb.

I don’t understand this at all. the length is immaterial* to how much force you can apply via the skewer lever.

*if we discount the difference in strain that 5mm extra makes.

Yes, that is what I was thinking, how many turns do you need to be getting on the skewer but, I can probably measure how far it is screwing in. I have another shimano one which came with the wheels originally but it is a cheaper looking metal version and when locking seems to stay level whereas the other shimano skewers I had fitted have a nicer feel to the finish and when locking go inwards just giving a better feeling of engagement.