@dErZ your van may not look low to you, but any van running Solow is towards the extreme end of lowering. With a 255/45 18 it’s no surprise to me that the fronts are rubbing. It’s already been said, but these vans were never intended to run at the ride height that us Solow users run them and there are always compromises. I have a few observations of your van.
1. You have some adjustment left on the front, maybe 5mm, so you could raise it a little if you wanted to.
2. I think you’ll still get rubbing if you did go up that 5mm. The rubbing you’re getting isn’t going to be solved with a 5mm ride height raise.
3. A heat gun and some moulding of the liner might help, but there’s one spot that it definitely won’t. There’s a shoulder in the liner towards the outside in about the 2 o’clock position passenger side and 10 o’clock position drivers side and you look to be getting a rub here too. This is because there’s a metal edge behind it, so you can only solve this by cutting this metal away, something that is sometimes done on vans running air to enable the really big drops.
4. Those FK510s do look wide on the fronts. They’re a great tyre, I’m a big fan and use them myself (in a different size), but they do look wide. A cheap budget tyre with less rim protection might help reduce the rub, they are typically narrower size for size.
5. I always explain to Solow customers that rubbing can be a problem, even at full height, especially when running load rated tyres. This is one of the compromises when choosing this suspension.
6. No two vans are the same, well, not exactly the same, and as such it’s really hard to make comparisons from van to van. Manual vs DSG, 4 motion vs 2wd, kombi/PV/Caravelle/any other variant, the owner’s regular load and other variables can make a difference between a rub or no rub at solow drops. Some vans will be OK at your ride height with that size tyre, some won’t.
7. A smaller tyre without the required load rating will help stop the rubbing, but is that a route you want to go down?
I run Solows at 125mm down on my own van and I’ve made a few compromises and mods to get there, but I still get rubbing. My arch liners have got more holes in than a Swiss cheese and my under engine tray is a mess, but it’s my personal choice to run that low and I accept it.
Solows aren’t something I recommend to anyone else without first discussing the associated issues and compromises that they would/might have to make.
As a summary from all of that, you might just have to accept that rubbing if you want to run that wheel+tyre+suspension combination.