The tyre industry is under growing pressure to optimise its use of raw materials and reduce emissions. One step is to use the circular economy as much as possible. Examples of this include recovered carbon black (rCB) and  recovered fuel oil (rFO) through pyrolysis technologies. Traditionally, carbon black was relatively inexpensive, but prices are higher and more erratic as a result of sanctions on Russia, in normal times the biggest supplier of carbon back.

Carbon black (sometimes called “char”) is generally added to off the road (OTR) tyres to improve strength and wear resistance. It is used as a reinforcing filter, so helps enhance the tyre’s durability and reinforces its structure, preventing cracks and deformation under heavy loads. Carbon black also helps to conduct heat away from the tyre,  reducing the risk of overheating during extended usage. According to Magna Tyres, global production of carbon black is around 15 Mtpa (pre-Ukraine invasion data) and the tyre industry accounts for around 73% of its consumption.

Adding it

Continental Commercial Specialty Tyres (CST) has now added rCB to its newly produced Super Elastic solid tyres at its tyre plant in Korbach, Germany.  Solid tyres such as CST’s SC20+ already contain around 60% renewable and recycled materials thanks to their high natural rubber content, says the company. By 2050 at the latest, Continental aims to use 100% sustainable materials in its tyre products.

The rCB is supplied by Pyrum Innovations, one of Continental’s partner companies. Pyrum breaks down end-of-life-tyres into their individual components in industrial furnaces using a special pyrolysis process. This allows valuable raw materials contained in end-of-life-tyres to be extracted and recycled.

“In Pyrum, we have found a partner that has developed a particularly efficient pyrolysis process. Together, we want to further develop the process for the pyrolysis of end-oflife tyres,” said Matthias Haufe, head of Material Development and Industrialisation at Continental Tyres. In the future, rCB will also be used in other Continental compounds. Jointly with Pyrum, the tyre manufacturer is currently working on further optimising and expanding the recycling of end-of-life tyres using pyrolysis.

Another pyrolysis furnace operator is Contec, a Szczecin, Poland-based company specialising in the recycling of end-of-life tyres. It says the market for rFO (also known as Tyre Pryolysis Oil, or TPO), will grow by a CAGR of 2.9%between 2021 and 2031. Contec typically achieves the following results through the pyrolysis process: 40% TPO;  33% rCB; 15% recovered steel; and 12% recovered gas. Most of TPO’s uses are outside the tyre industry (heating, power generation, power generation), but it can be used as an alternative to fuel-based feedstocks in producing carbon black.

Solid citizens

Solid tyres have a high load capacity relative to their size and are extremely stable, punctureproof and virtually maintenancefree. They are mainly used in the material handling industries and for equipment such as FLTs, airport vehicles, heavy transport vehicles, sideloaders, platform trucks and other industrial vehicles.

The limiting factors are travel distances and speed (heat buildup), so heavy load factors can be obtained only by using larger pneumatic tyres. In the ports industry, there is no alternative to  pneumatics on equipment from terminal tractors and trailers all the way to heavy FLTs, reach stackers, straddle carriers and AGVs.

Electric downsides

Whether super-elastic or pneumatic, low rolling resistance compounds are becoming more important than ever. Most FLTs in intralogistics type services, such as in warehouses, are already powered electrically and electric drivelines are now making an impact in trailer logistics and port applications.

Range and charging times of the battery employed are key issues. Tyres with a low rolling resistance can help lower the energy consumption of electrically powered machines and contribute to extended travel times. The conundrum is that tyres are subject to more wear, as battery electric machines are heavier than their diesel counterparts. In  addition, extra stress results from the instant torque and the higher inertia factor means braking distances are longer.

EV downsides

One of the promises of EVs for port operators is lower maintenance due to fewer moving parts, no oil changes, simpler drivelines, and so on. However, potential downsides are often overlooked.

Because EVs are still rare in port handling equipment, the ports industry has no benchmarks to reference tyre wear, but road experience provides a clue.

One leading fleet tyre company, ATS Euromaster, has warned that fleet operators making the switch to EVs must expect a significant shift in the balance in their service, maintenance and repair (SMR) spend. “While EVs are expected to cost less to service, tyre life expectancy is likely to be shorter with traditional internal combustion engine (ICE) fleet vehicles,” said ATS.

Since car and road truck tyres last longer than heavy equipment tyres, heavy plant operators may need to prepare for much  bigger expenditures on tyres. Unfortunately, this will encourage a switch to cheaper replacement tyres (unless legislation prevents this), which is clearly a false economy, because they will not withstand the duty cycles required of them.

The analogy here is using road truck tyres on terminal tractors, on the basis that they are readily available and relatively inexpensive to buy. This remains common practice – even OEMs sometimes have to fit them because the customer wants to save money. However, the compounds and structure (eg shoulder) are different, the load factors even more so, and downtime to change tyres increases.

For the time being, heavy mobile port plant remains hard to electrify, but it is appearing in greater numbers as the price:performance ratio of the batteries continues to become more favourable for customers. There are no data available on tyre wear comparisons, but in due course one can expect to see modified tyre designs, or different machine designs.

One obvious example is the steer tyres on heavy counterbalanced lift trucks. When travelling empty, two steer tyres have to support almost as much mass as the four drive axle tyres and abrasion when turning leads to accelerated wear.

Extra wheels

WorldCargo News has reported recent developments with very heavy reach stackers from CES Srl designed to handle offshore  wind tower sections. The 200t capacity unit has five wheels on the front axle. On top of that, the new 350t machine has four wheels on the steer axle, with a bogie arrangement on each side of the counterweight. Could we,  in future, see a similar arrangement with, say, reach stackers built to (un)load barges? The CES HLM 3500 machine has a wheelbase of 13m in the “closed” position, extendable in 1m increments to 18m. It is shod  with size 36.00-51 tyres on the front axle. The rear axle tyres are size 24.00-35. As previously discussed, the normal 10bar tyre pressure is provided through an 80:20 water:air mix. This helps keep temperatures down and reduces the risks associated with a  blow-out.

What about tyre sizes on “regular” machines? Regular laden container handlers are fitted with 18.00-25 tyres all-round, but  reach stackers with 35/36t second row capacity and/or intermodal handlers designed to lift over the second rail are generally fitted with 18.00-33 tyres all-round, to spread the higher imposed loads over a larger “footprint.” As they  are of course bigger than 18.00- 25 tyres, they rotate more slowly and that translates into lower tyre wear.

Paradoxically, bigger, slower tyres may make for a better environment as reduced wear means fewer particle emissions.  Tyre makers are working on new compounds to reduce the toxicity of particle release. However, the drive to electrify vehicles and eliminate exhaust (tailpipe) emissions is making the problem worse, for the reasons discussed above.

In the US and Europe, regulations are being drawn up to limit material loss through wear and abrasion. It is not yet clear whether this will affect off-road equipment. If it does, port equipment could be amongst the first in the firing line, since machines run on hard made-up surfaces. It is also unclear how legislation will affect  replacement tyres, a huge market in the ports industry.

Another point concerns tyre monitoring. Leading tyre makers are now fitting OTR tyres with  temperature and pressure monitors as standard, and offer telematics for real-time monitoring. Maintaining the right pressure (10bar) and hence temperature is key for maximising tyre life.

Operators of EVs may start to notice higher temperatures as accelerated wear reduces the circumference of the tyres so they rotate quicker. Thus, there is no substitute for visual checks of remaining tread depth.

It might be objected that CHE is very heavy in any case even without batteries, so to apply context, the nominal circumference of a 16.00R-25 straddle carrier tyre is around 4.6m, to it completes 217 revolutions per km travelled. From the tyre maker’s standpoint, a balance has to be struck. If the original tread  is too thick, the tyre is exposed to tearing and faster temperature and pressure build-up.

New products

The last two tyre surveys from WorldCargo News have featured new reach stacker/heavy FLT tyres from Yokohama TWS  (Trelleborg Wheel Systems), Nokian and Michelin, the new straddle carrier tyre from Bridgestone and the new dedicated AGV tyre from Michelin.

Another recently introduced reach stacker/heavy FLT tyre is the Port King Classic from India’s BKT Tires. This IND-4 tread tyre  features a strong nylon casing, designed for higher load capacity while minimising the risk of impact breaks, snags, and punctures. A new wear-resistant compound has been developed to ensure an extended product life cycle, and to  provide the best return on investment. It is currently available in 18.00-25 size, generally used on reach stackers with a maximum second row capacity of 31t. 

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This complete item is approximately 1630 words in length, and appeared in the November 2023 issue of WorldCargo News, on page 30. To access this issue download the PDF here