Important information relating to fitting and removing Run-Flat Tyres (RFTs)
The Run-Flat Tyre, also known as RFT and SST (Self-Supporting Tyre), is a common feature in todays car park, and its effect on the garage equipment manufacturing industry has been one of huge influence. You don’t have to be in the tyre business to have heard of RFTs, they are now a reference most consumers will be familiar with, even if it is not always fully understood.
What we will discuss here is the effect they have had on the tyre changer market, having forced a total change of direction on the product and people’s buying habits over the last 2 or 3 decades. When considering a new tyre changing machine, the ability to handle RFTs should represent a large part of the decision, but all too often it isn’t. Here we will attempt to shed some light on this and provoke some thought on the crucial aspects of a tyre changer in this day and age.
This may surprise many, but the concept of an RFT isn’t a new one. It isn’t even a product of the modern era. In fact, the first patent for a Self-Supporting Tyre (or Tire, actually) can be traced back to 1892! However, it was in the 1930s when Run-Flats really first came to prominence, being used on Military and Armoured Vehicles (for obvious reasons!). It was Michelin who dominated that particular sector, a company who were to retain an association with this style of rubber until this very day.
In the ’50s Chrysler commissioned Goodyear to develop an RFT, and there may even be some reading this who can remember the Dunlop Denovo of the 1970s!
But it is the arrival of the 21st Century that really saw the RFT become a much more cost-effective, technically feasible and more accepted addition to passenger cars. Arguably, Bridgestone and Pirelli were at the forefront of the mass market, partnering up with the likes of BMW to almost standardize the inclusion of RFT’s on a mainstream range of vehicles.
Products like Bridgestone DriveGuard, Pirelli Cinturato P7, Michelin ZP, Goodyear Eagle F1, and a host of lesser known brands are now readily available and reasonably priced in relative terms.
This means no one is really immune to having to deal with them, and anyone who has attempted to change an RFT on a basic tyre changer will know the difficulties they present.
So what makes them such a challenge? Well when you are changing a tyre, the elasticity of the bead plays a huge role in how easy or difficult the tyre is to handle. Regular, more traditional ‘baggy’ tyres with high profile sidewalls are all easy to deal with, because you have so much ‘play’ that levering the bead over the demount head isn’t much of a task. With an RFT, however, the sidewall is made to be deliberately tough, being reinforced and eliminating the flex associated with a normal tyre. This means it doesn’t have the ‘give’ when levering the bead over the demount head, and this can put a huge strain on the machine, the tyre lever, the bead itself, and even the operator!
The diameter isn’t the issue here; just because you buy a machine that’s claims clamping capability of up to 24” does not mean it is suitable for removing even a 19” tyre. It is the profile of the tyre that really makes for the main issue, with 35 or 30 series proving the most difficult. Short, thick, reinforced rubber provides the tyre machines’ wortst nightmare!
Why they’re tough: Very short sidewalls mean less give, making it difficult to lever the bead over the rim.
So what should you look for when choosing a machine to handle these difficult tyres? Well, there are 3 key things you can look for when determining the suitability of a tyre changer for RFT applications, most notably:
Assist Arm – Also known as Help arm, robotic arm, 2 way or 3 way helper, when they were first introduced back in the ’90s they were commonly know simply as ‘a 3rd arm’. This was because the tyre fitter, already sporting 2 arms, really needed that additional arm to hold the bead down. This often resulted in 2 tyre technicians having to work together on one tyre!
The purpose of the assist arm is to provide pressure, normally via pneumatic power, to manipulate the tyre in the right places to help get the bead over the demount head. Typically, this means a depression of the bead into the ‘well’ of the rim at the 6 o’clock position directly opposite the demount head. This gives some release at the crucial area being levered over. An additional pressure point will then come from a roller located just to the side of the demount head, which will help get the lever inserted into the bead. More recently, an additional roller is often introduced for the larger diameter rims, to provide a vital 3rd point of depression on the tyre, effectively to stop it popping back on the rim again as the turntable is rotated.
The ’Assist Arm’ is, aside from the odd tyre technician whose pride may still get in the way, an essential part of a tyre changer today. To buy a machine without the additional arm, is almost like only buying half the machine nowadays. Training is crucial to get the best out of the assist arm, and so it is always wise to look for a supplier who can provide this if you are not already familiar.
Giuliano were at the forefront of the development and introduction of the Assist Arm, and the HP series has been widely copied (but never truly equalled) by large number of manufacturers. Additionally, Giuliano promoted the use of 2 additional assist arms, known as the Help and Press, which provide the ultimate ease of handling RFTs, but that’s another story in itself.
Leverless Operation – removing the manual tyre lever from the process of tyre fitting and removal provides a number of advantages for the operator, the machine and the tyre. Firstly, whole process is automated at the touch of a thumb control. Instead of having to provide manual leverage to lift the bead of the tyre over the edge of the rim, the operator simply presses the thumb control to lower the finger or ‘hook’ into the tyre, and presses again to activate a lifting motion which sees the bead comfortably hooked back over the bead. One of the crucial points here is that you are lessening the need to stretch what is a tyre sidewall which effectively has no stretch. The usual thickness of the tyre lever and the demount head is replaced with the thickness of the hook only, putting far less stress on the tyre and the machine. Clearly, for the operator this means a much easier and safer working practice, removing the fear of damage to the tyre or even damage to the body, with bad backs being a common complaint amongst tyre fitters! In the late 2000s, Giuliano reinvented the capability of the tyre changer by introducing the QX system, which is a leverless system that can be fitted, factory or retrospectively, to a conventional tyre changer. Today, around 50% of the Giuliano models sold in the UK will go out with a leverless device fitted, or updated later when the customer wants to improve the function of the their machine without having to buy a whole new tyre changer.
Strength of the machine – this is, 9 times out of 10, completely overlooked. To the untrained eye, one tyre changer looks much like another, but there is a reason why the price of tyre machines vary so dramatically. The stresses put on a machine during the process of fitting run flats is immense. Every single element, from the chassis (stress on the turntable can visibly ‘bow’ the top of a chassis on a cheap tyre machine), through the main column (the length of which can introduce flex and movement), down to the demount head (lots of moving components all act as an opportunity to introduce movement), all play a role in how long the machine will last and how many tyres and rims it may or may not damage along the way. To put this in perspective, a couple of mm of movement in the main column alone can result in a centimetre of movement at the demount head, and the one thing you want is for the demount head to remain as rigid as possible under stress.
Things to look for in a strong tyre changer is the design of the main column. Giuliano SX228 and SX229 tyre machines, for example, use a tapered, 2 piece turret and a cylindrical turret respectively, both of which provide far more rigidity than a traditional box-section turret which is much cheaper to source.
However, the most significant development in recent years is the introduction of the Par-Move design, which is featured on the SX229 Pro. Par-Move (Parallelogram Movement) combines the space saving benefit of a swing arm, with the ease of use of a tilt back, but provides a far superior strength than both, making it a trifecta of improvement! Over the coming years we expect to see the Par-Move system replace traditional tilt-back designs in the same way the tilt-back did to the swing-arm.
Whilst this may seem a comprehensive overview on Run-Flat Tyres and the best method for handling them from a fitting and removal perspective, in actual fact there are still so many factors that can have a huge bearing, including bead-breaking, which is another subject we will save for another day.
In the meantime, the best solution to ensuring you make the right purchasing choice is to actually see the machines in action, and at our Cambridgeshire based showroom we are able to offer demonstrations of the full range of tyre machines, complete with an array of exotic rims and difficult tyres to prove the various merits. Visitors are welcome by appointment, which can be arranged by calling one of our team on 01733 920440.