Flat-Spotting (tyres)

I have never noticed this before on any of my previous tyres or cars, but I am getting 'flat-spotting' on my Maxxis worm-drives, does anyone else notice this?

Here is what happens, park the car up over-night or more likely a couple of days, get in it and set off down the street and it feels like you have something stuck in the tyre (a bit of mud), it goes 'dunk--dunk--dunk' down the road for the 100m or so, after that it is fine.

What is actually happening is the trye is deforming slightly with the weight of the car and creating a slight flat spot.  I checked the pressures, all about correct for a Jimny, so I don't know if this is a feature of the worm-drives or if I need to raise the pressure a little?

I am not overly worried about it and don't think it is doing any lasting damage as it soon goes.  I know the army used to raise their vehicles up on blocks when not in use to stop flat spots on tyres (I am thinking of Green Goddess here).

Robin

It can happen if a vehicle is left for some time, I am thinking classic car in storage over winter. A suggestion is to over inflate the tyre during storage to reduce the "flat spot", but it's not something I personally have ever seen. My 2CV and Land Rover often spend months stationary, both have never exhibited this problem. 
My Jimny has just spent 2 weeks on it's Yokohama tyres whilst I did the Kingpin, again no issues. Did you see this when you had different tyres fitted?
If not I would conclude it's your current tyres, is it possible are they old stock or it's a construction feature?

As you say it's not an issue after the first few revolution's of the tyre, but an interesting question if anyone else has seen this.

Hi, running the worm drive myself, and don't use the car for about a week each time, and don't notice any issues.

I would be alarmed if any of my tyres exhibited such alarming tendencies. The fact that they deform in a matter of hours and then correct the issue so quickly leads me to believe there is a problem over the internal assembly of the tyres. Definitely one for the makers to be informed.

Roger

We over inflate the tyres for winter storage, James' Jimny is at 45psi in the garage at the moment

Is this in the very cold? perhaps the side walls are very stiff in the cold?

It’s probably more noticeable in the cold. I had the worm drives fitted just before Xmas and noticed it for the first time sometime in Jan. it’s quite slight and goes by the time I get to the top of the street, so it might be temperature dependant. It is one of those things once you notice it once you are on the look out for it and I doubt anyone else would notice it unless prompted.

When it’s not raining and the car has stood for a while, I am going to re-check tyre pressures just to make sure one isn’t low.

I did wonder if it was a brake binding, but couldn’t work out why it would only happen in a morning, but it just occurred to me, maybe it’s the handbrake and possibly slightly oval hubs?

The drums are almost bomb proof, more likely to be a sticking front caliper slider pin.
Only suggesting this as my recent "judder" tended to manifest at the beginning of a Journey.