The marks TL and TT describe how a tyre holds its air. TL means tubeless, the standard on modern cars, where the tyre holds air directly without an inner tube. TT means tube-type, a tyre that needs a separate inner tube, once universal, now rare.
Tubeless tyres (TL)
A tubeless tyre holds its air without an inner tube. The tyre and the wheel rim form an airtight seal at the bead, and a thin rubber inner lining inside the tyre keeps the air contained. This is how virtually every modern car tyre is built, so common that the TL mark often goes unnoticed.
The advantages are why tubeless took over. With no tube to burst, a punctured tubeless tyre tends to lose air gradually rather than suddenly, giving the driver more warning and more control, a principle taken further by run-flat tyres, which hold their shape with no air at all. Minor punctures can often be repaired from inside the tyre, and the design runs slightly cooler without the friction of a tube.
Tube-type tyres (TT)
A tube-type tyre cannot hold air by itself and relies on an inner tube fitted inside it. This was the original design for all tyres, but for cars it has been replaced almost entirely by tubeless.
Today a TT marking is mostly seen away from ordinary cars, on some classic and vintage vehicles with the wheels of their era, on certain motorcycles, and on agricultural and some trailer tyres. For everyday drivers it is a marking they are unlikely to meet.
Which a tyre needs
The rule is simply to use each tyre as it was built. A tubeless tyre is designed to run without a tube, and a tube-type tyre must have one. Fitting a tube into a modern tubeless car tyre is occasionally done on particular wheels as a workaround, but it is not generally advised, and any such exception is worth getting proper advice on rather than guessing.
For the vast majority of drivers the matter never arises: the car came with tubeless tyres, any replacement will be tubeless too, and the TL on the sidewall confirms it.
From the workshop: in years of fitting car tyres, tube-type is something we mostly see on classics and the odd trailer. If a customer is restoring an older car on its original wheels it can matter, but for a normal modern car it is tubeless every time.
Common questions
What do TL and TT mean on a tyre?+
TL means tubeless, the tyre holds air without an inner tube and is standard on modern cars. TT means tube-type, a tyre that needs an inner tube to hold air, now rare and found mainly on classics, some motorcycles and agricultural use.
Are car tyres tubeless or tube-type?+
Almost all modern car tyres are tubeless. The tyre and wheel form an airtight seal, with an inner lining holding the air, so no separate inner tube is needed. Most drivers will never encounter a tube-type car tyre.
Is a tubeless tyre safer than a tube-type?+
Generally yes. A tubeless tyre tends to deflate more slowly after a puncture rather than suddenly, because there is no tube to burst, which gives more warning and control. This is one reason tubeless became the standard for cars.
Can you put a tube in a tubeless tyre?+
It is sometimes done as a temporary measure on certain wheels, but it is not generally recommended for modern car tyres, which are designed to run tubeless. The right approach is to use each tyre as it was built, and to seek advice for any exception.