The animal welfare body is asking the public to be extra vigilant if they keep wheels on their premises to store them carefully to avoid another incident.
The charity explained that when foxes become trapped in wheels they put their heads through the middle hole of a wheel, maybe searching for food, but then find to their dismay that their ears stop them from reversing out.
The first rescue case, Rodney Kenny, an RSPCA animal welfare officer, rescued a fox from a car wheel in Orpington on April 22.
Just a couple of weeks later Nick Jonas, another animal rescue officer, was called out to an incident in a garden in Newham, East London on May 5.
Animal Rescue Officer Nick Jonas said: “Young foxes are incredibly curious and we quite often get called out to deal with ones that have got themselves in a pickle.
“But in my experience, it’s quite unusual to get four ‘head stuck in wheel’ incidents in just one month.
“They put their heads through the middle hole of a wheel, maybe searching for food, but then find to their dismay that their ears stop them from reversing out.
“In situations like this, there’s no time to spare.
“They may have been trapped for several days without food or water, so need to be freed as soon as possible.
“There’s a bit of a knack to freeing fox cubs when they get their heads caught, as it’s their ears that are the problem.
“With both the recent incidents I attended, I found that gently easing the little foxes’ ears one-by-one back through the hole made it easy to free the animals.
“Thankfully, both appeared to be in good condition, despite their ordeal so I took them to the South Essex Wildlife Hospital where they will be rehabilitated until they are ready to be released back into the wild.
“And I understand that the other two fox cubs my colleagues rescued from similar predicaments are happily also unscathed by their ordeal.
“We’re asking the public to be extra vigilant if they keep wheels on their premises.
“Please store these items carefully and check them regularly, just in case another fox cub traps itself.”
The RSPCA has advised people to not try and free wild animals by themselves.
“Wild animals can scratch, kick and bite when frightened, particularly if they are injured so you could risk hurting yourself and the animal.
“Many animals that become trapped or tangled can be more seriously hurt than you think, so it is best that they are examined properly to see if they need treatment.
To report concerns about an animal, please contact the RSPCA’s emergency line on 0300 1234 999.