Retreading car tyres is unusual in may parts of the world. But retreading a tire for an airplane is common practice. Read this post, which is written for curious flyers rather than the aviation industry, to learn more about the practice and the process of retreading airplane tires.
It is common practice to buy new tires for our cars, once the tread has worn out. In aviation, things are a little different.
The tread of an airplane tire will wear out long before its casing (everything other than the tread). This means that the tire casing remains entirely capable of safely holding the inflation pressure to support the load of the airplane long after the tread has worn away. All the tire needs is a new tread.
Airplane tires can be expensive: there is no logical reason to scrap a tire for an aircraft when it can be safely and economically reconditioned with a new tread. This is why retreading has been standard practice in the aviation industry for decades.
Retreading an airplane tyre is not a perpetual cycle: each tyre part number is limited to a set number of retreads which reflects its safe retread limit.
The maximum retread level for the part number is set only after extensive testing and analysis. Some airplane tyres can be safely retreaded up to seven or more times, but there is always a limit and the limit is always set with an abundance of caution.
The retread process is easy to understand.
- A worn tyre is removed from an aircraft.
- It is sent back to a retreading firm, often a manufacturer of airplane tires, such as Dunlop.
- When Dunlop receives a tire for retreading it is carefully inspected to ensure that it is safe and economical to retread.
- The tyre is scrapped if Dunlop’s technicians consider there to be doubt about its airworthiness.
When the tyre is deemed safe to retread:
- Remaining tread will be removed.
- New tread rubber will be wound on to the casing.
- The tyre will be remoulded.
Once the manufacture process is completed, the tyre will undergo sheareographic inspection. This inspection enables an operator to ‘look inside’ the casing of the tyre to ensure all-is-well prior to a final multi-point visual check and balance.
And again, if there is any doubt as to the airworthiness of the tire, it is scrapped.
The process is simple to understand, but the details at each stage are incredibly complex. For this reason, the aircraft tire retread process can be carried out only by companies that hold appropriate approvals.
Aircraft tire retreaders are extensively and repeatedly audited by airworthiness authorities such as the FAA, EASA, or the airworthiness authority of a nation state. This means that the aircraft tyre retreader may only carry out their business with approvals to mandatory airworthiness regulations such as EASA Part 145.
If you have flown on a commercial airliner, you have, in all likelihood, taken off and landed on retreaded tyres which, thanks to the robust regulatory framework, are entirely safe and manufactured to a high standard.