They say that necessity is the mother of invention.
Faced with the relative rarity of tire shops that can accommodate Citroen wheels, local member Terry H and I set out to solve the problem. Admitedly, Terry and I are die-hard do-it-yourselfers, so a challenge like this is as much about the fun of finding a solution as it is about practicality.
The problem stems from the fact that Citroen wheels lack a large centre hole. In most modern cars that hole has become a standard, used to centre the wheel on the hub, before tightening down the wheel nuts. When our beloved Citroens were conceived there was less standardization and the engineers at the home of the Double Chevron opted for wheels with simple domed centres.
Fast-forward a few dacades, and tire changing machines have evolved to rely on that centre hole design. As a result, many shops feel they are unable to mount tires onto our wheels.
It is possible to mount tires just using three long tools called tire irons, working manually around the circumference of the wheel. However, having done that myself in the past, I can tell you that it is a very physical task, and can be very hard on the tire.
Tubeless tires fit very snuggly to the outer lip of the wheel. The stiffest portion of the tire, the bead, needs to be pried over the rim (edge) of the wheel when mounting. Modern powered tire changing machines still rely on a fairly simple principle, which is to stretch the bead at just one point, while rotating a lever around the rim. Often, a post that sticks up through that famous centre hole is used as the point of leverage. The lack of that centre hole in Our Citroen wheels therefore is where things break down.
In looking around, I discovered that Princess Auto (similar to Harbor Freight in the US) sells a manual version of the typical commercial tire changing machine. Turning to everyone’s favourite information source, I uncovered a nice (but long) video on YouTube showing how the machine works.
Terry and I had a good look at things, and figured there must be a way to adapt such a machine to handle Citroen 2CV wheels. The quest was on. In my mind, I had a general idea of what we needed: 1) a way to secure the wheel to a flat top plate; 2) a way to mount a strong centre post on top of the wheel, around which we could rotate the long pry bar.
The first part was fairly simple. Terry welded a strong thick plate to the threaded top cap of the tire machine (the bottom of that cap normally is used to tighten the wheel down). To that plate, he attached three bolts which act like wheel studs. So, the wheel on which the tire is to be changed just fits over the three studs, and sits horizontally on the strong plate.
The second part was a little tougher to solve. I did some Google searching, and uncovered two patents from the early 1960s that addressed exactly the second half of our challenge (the strong centre post). At the time, the inventor Victor Duquesne aimed his solution at several marques of cars whose wheels lacked the centre hole (Citroen, Renault, DAF among others). At that time, this probably was a daily problem, and so was worthy of his attention.
I sketched up a possible approach based on the drawings from the patent. Terry reviewed it with his experienced eye as a welder and fabricator. He was pretty sure my plan would not be strong enough. He felt that I had underestimated the huge forces that are involved. Later experience shows that he would have been right.
Together, we discussed alternatives. We eventually settled on a design that uses the centre section cut out of a 2CV wheel (the part where the wheel nuts go). Onto that Terry welded a very strong tower, with a wide base to spread the loads.
So, basically we have wound up with a three layer sandwich: there is that flat plate on the tire machine, with three stud facing up; the subject wheel is placed on that plate, with the studs extending through it; the tower is then placed on top of the wheel, over the studs, and the whole things is clamped together with nuts (as if they were wheel nuts on the car). Of course the photos make the whole thing clearer.
But would it work?
Terry and I grabbed an old wheel (from that 1964 2CV that we rescued at Ted and Laura’s place), as well as an older tire that had been removed from Bob’s car many years ago.
The verdict: SUCCESS! We are more than thrilled with the result (but you can see our Tips page here)
Our next step will be to mount Bob’s new tires. See that story elsewhere on the site.