700c flat spot; any ideas?

Went out for a ride on Saturday and was getting a judder from the front wheel. Initially I thought it was the road surface, but on closer inspection discovered a localised flat spot. I initially thought there was a problem with tyre bead seating or inner tube. Deflated and inflated, flexing the tyre and increasing pressure. Changed the tube but to no avail! Checked the rim and even swapped from front to back wheel, but still no joy! Any ideas from the Singletrack massive…? Loads of tred left, but could it be new tyre time?

Bump for the mid week crowd!

Too many skids

It’s not tyre wear, it’s difficult to spot without turning the wheel at a constant speed. Not sure what to make of it?

Sorry I’m a bit lost. So it does it even with the tyres swapped?

Is there a noticeable flat spot in the rim when you spin it with no tyre?

No, the rims are fine. It’s like a “gimp” in the tyre itself. I thought it was the inner tube, so swapped over, but still has some form of localised deformation. It’s a Schwalbe super swan.

tubeless ?

are you sure the beads are fully seated ? (lots of fairy liquid for inflating)

(I did have a nobby nic once that had a deformed carcass and wouldn’t seat or ride properly)

Are you saying that going tubeless may solve the problem?

I’d wager it is either braking flat spot(s) or the beading is not sitting properly.

I had the latter with my Jumbo Jims recently, caused major wobble as the wheel rotated, then checked to find the beading stitching was ~0.5cm or so out in a section of tyre compared to the rest. Deflated, squeezed tyre and tube all around wheel, re-inflated and sorted.

In order of likelihood: Bead seating, braking flat spot, rim damage. You would remember the sort of impact that causes rim damage (I cracked an Open Pro right through to leave 0.7 mm flat spot), you can feel a braking flat spot (and see the missing tread), so that leaves bead seat. Deflate and wiggle tyre from side to side checking no inner tube is pinching. Reinflate.

If it still persists, swap with the front. Rear is always more noticeable.

Well I’ve swapped tyres and Inner tubes with rims and can confirm that there’s nothing wrong with the rims. The one good tyre seats perfectly on both. I’ve tried different inner tubes with the rogue tyre and get the same problem. Essentially, the tyre, a wire bead will not completely seat all the way around the rim. I’ve tried increasing the pressure but cannot get it to seat over a 200mm section, which creates the flat spot. I can’t fundamentally see any difference between the two tyres and it’s doing my head in!
Sorry, rant over. I think I’ll be taking it to my lbs and see if they have the answer. Thanks all for the replies.