Frequently Asked Questions

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How can I convert my tyre pressures from bars to psi?
From bars to psi multiply by 14.5034. From psi to bars multiply by .06895 (or divide by 14.5034)

How do I calculate the revolutions per mile of my tyres?
To obtain the true figure you should take the deflection into account and start with the diameter (in inches) less tread height. Therefore the calculation should be; tyre diameter (less 2x tread depth), multiplied by 3.142 to get the circumference, you should then divide 63360 (which is the number of inches per mile) by the circumference to obtain the revolutions per mile.

Why can't I run my Beaded Edge tyres at a lower pressure for a more comfortable ride?
Beaded edge tyres are "inflation held" unlike more modern tyres, they stay on the rim by air pressure alone. Reducing the pressure could allow the tyre to "jump off" the rim or lead to rapid tyre failure as the tyre chafes against the rim.

Why do my crossply tyres develop "flatspots" when I leave my car parked for a few days.
As the vehicle travels along, the tyres rotate and flex. This action generates heat within the casing of the tyre as the cords move. When the vehicle stops the weight of the car presses down in one place and the tyre's cool down, this can sometimes cause the tyre to "set" or develop a temporary flat spot. During the next drive the tyre warms up again and the process is repeated. To stop or significantly reduce this cycle, raise the tyre pressures by 2 or 3 psi this reduces the flexing and therefore reduces the heat generated.

My car has wire wheels but I can't find tube type tyres, so can I put tubes in my tubeless tyres?
Most manufacturers except that it is safe to fit tubes in tubeless tyres providing the correct size tube is used.

My crossply tyres have several size markings on them, why is this?
Some crossply tyres are dual marked, for example 475/500-19, this means that the tyre will replace both a 475-19 and a 500-19. It is therefore a compromise between the two.

Why can't I use treaded racing tyres on my road car?
There are several reasons why this is not advisable, racing tyres are built without compromise; they are generally a softer rubber so may not last long and could overheat, they have reduced wall and crown thickness to reduce weight and could be easily damaged. Racing tyres are also moulded with reduced tread depth offering limited water clearance.

Can I mix radial and crossply tyres on my car?
For the best performance keep the same construction of tyre on front and rear but yes, you can mix the two. By law you have to fit crossply on the front and radial on the back.

Is it possible to fit modern radials on my 60's classic car?
You can but the performance and durability of the tyre will deteriorate.

One of my beaded edge tyres recently came off the rim and I noticed it was quite rusty inside, are they safe?
The shape of the rim shares a high level of importance with the pressure, the nose at the tip of the clinch intrudes into the tyre forming a positive lock. However if this area is allowed to develop a sharp corroded edge it will rapidly cut the tyre bead. It is also common practice amongst restorers to cut this area back to provide a more sympathetic surface. This is a mistake and will lead to premature failure as it drastically reduces the support in this area.

My car is fitted with new beaded edge tyres but both front tyres have bulges on the sides, is this fault with the tyre?
From your description I suspect that the heel of the tyre has actually torn, leaving the side wall unsupported resulting in a side wall bulge. This is commonly caused by one of two reasons, the first and most common is under inflation, this allows the tyre to flex on the rim which in turn allows the nose of the rim to chafe and eventually cut through the toe. The second reason is poor rim condition, over the years it has become common practice to "cut back" or "tidy up" the nose on the rim edge to remove the sharp corroded edge, this is not good practice as it leaves the heel of the tyre unsupported when under load causing the rim to "skin off" the tyre heel.

I need to replace a tyre on my car but I can't find a local garage that can help, the tyres are 820x120 beaded edge.
I can understand tyre dealers and garages expressing concern as they are quite different from modern tyres. However, with a little advice and care it is possible to fit them yourself. Firstly with the tyre removed check the rim for condition if necessary we can provide a copy of the rim profile, check for crushed clinches, sharp and corroded edges etc.

Step1
Slightly inflate the tube and with some French chalk fit the tube inside the tyre.

Step 2
Offer the tyre to the rim and put the valve in the valve hole.

Step 3
With a beaded edge tyre lever, lever on the inside bead first, taking care to avoid pinching the tube, beaded edge tyres are like giant elastic bands so expect some resistance!

Step 4
When your satisfied that the first side is on correctly, work around the rim with the lever, you will find it easier with two levers at this point, one to hold the beginning in place and one to work around.

Step 5
With the tyre fitted rotate the tyre while bouncing on the ground to ensure the heels fit into the clinches correctly, when your satisfied that the tyre is fitted correctly inflate the tyre to 5psi, stop and check correct heel fitment and inflate to correct pressure.

Beaded edge lever have hooks at one end to avoid" tube nipping".

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