Hey guys took the bike out for a 300km ride yesterday. When I got home I noticed this big wear mark on the front tyre (Metz ME880). 

That's strange, while at first it may look like a rock caused it, there's signs that it didn't, i.e. the grooves are not affected therefore doesn't seem like a rub mark to me.  It almost looks like the tyre has collapsed in the middle due to low pressure.  What pressure is in it?

I’ll admit that I have been slack in checking the tyre pressures, and have no doubt that the 20psi that was in it is to low. 

I'd say that did it, 20psi is very low.

Lesson learnt, check tyre pressure regularly! Thanks chops. 

Still it’s weird looking wear, never seen anything like that before

Yeah, W.Glider correct. At times we, sometimes become lazy in checking things. As such going for our ride , daily or whatever. Must get finga outta arse and do some basic checks. Thanks for reminder to us  WG. is too true.

I wonder if it is the tyre delaminating as I have read a few stories on a American forum of metzlers doing it on rare occasions, I still use them though

Yeah pressure too low but I don’t think that’s the cause of what’s in pic... strange one

What was the pressure in the other tyre?  If that one was around the same and no similar damage occurred, you might want to investigate further.

Take it back to where you got it, still heaps of tread left

Tyre presure way to low as people have said. But also check wheel bearings. By look of wear pattern. Surely you felt slight movement in the h/bars from tyre flexing over road surface.  Buy a decent tyre presure guage. I use a VDO brand. Try not to trust servo guages

Contact Metzler and supply the photo and description , they are best placed to assess your tires condition. It does not look like de-lamination as that condition involves the tread area/side wall coming away from the carcass ,it is interesting how the compound erosion distorts around the grooves.

I have emailed metzeler and am waiting for a response. 

Gotta be low pressure. I dunno how you could ride it with 20 pounds in the front.

Any less than about 32 in the front of my ol' Superglide and it feels real doughy in the front end.

My first thought was that the tyre has got VERY hot on that centre part. The lower the tyre pressure the more the tyre deforms over bumps etc and gets very hot at that contact point.  The same happens with a race  bikes when the tyre surface gets too hot due to overinflation. This over inflation causes the tyre to heat up quickly, and unevenly. The surface of the tyre gets hot, whilst the carcass is not yet up to temperature. This can see the polymers in the tyre, which hold everything together, start to give way causing the tear. My 2c worth

Correct me if I'm wrong but I think tyres only have a 5 year life span. Most blokes these days wouldn't do many miles in five years, I have met blokes with ten year old bikes that still have original tyres on board. Looks like the compound has disintegrated and come away, possibly due to age. Just because you buy new tyres doesn't mean they are less than five years old, they may have been on the shelf for yonks. 

Good point, tyres do have a relatively short shelf life. Possibly the issue the O.P has is the combination of old expired tyre with insufficient air pressure. 

Just an update boys, I have had the front wheel off, no signs of damage under the guard and the wheel bearings all appear to be fine, still waiting on a reply from metzeler.

If something was rubbing on it the groove cut would have been symmetric in shape, and not deviated around the tire grooves as in the picture.