Designation` 3TM,6205 X30/26 Type` Deep groove ball bearings.Single row, without filling slot. Complete. (26X52X15).
bearings 52 x 26 x15mm | Adventure
The largest hole in the middle of a 52mm bearing is 25mm (6205) Your KTM front end standard bearings are 47 x 30 x 9 (6906) so it's a 30mm axle. The nearest to 52mm with a 30 mm bore is a 55 x 30 x 13 (6006), so that means boring the wheel , Me I'd sell the wheel, lots of older road bikes with spoked wheels and reasonable brakes use 47mm bore.
NTN 6202 Deep Groove Ball Bearing | WS BEARING
Home NTN BEARING NTN 6202 Deep Groove Ball Bearing. NTN 6202 Deep Groove Ball Bearing. Brand·NTN. Category·Deep groove ball bearings specifications. Brand model·6202.