[JOHN SECCHI]

The guide is just a push in fit, they do require some force to remove.
The later re-issed kits that were available in the 80's came with a deeper guides which worked ok on most tracks with the original tyres but these are hard to find.
If you want to race these then truing the tyres will be your only option without major surgery to the chassis.
[oneofwos]

 

[JOHN SECCHI]

Ortman replacement tyres, including the front round ones, are available for both the ball race and slimline MRRC cars.
The very last version of the ballrace RTR guides used the modern push in braid and clip and looks to be a modified Le Mans guide, it will not fit the Slimline cars.
[oneofwos]