What is a big single child?
The scientific name for large single tires is “wide cross-section tires”. Internationally, it refers to tires with cross-sections above 385mm. China’s policy advocates the use of large single tires above 400mm for trucks.
Only one tire is required on each side of the axle with large single tires.
What are the advantages of a big single tire?
The advantages of a large single tire are many. After the implementation of the 9.21 New Deal, the reason why car companies adopted a large number of such tires on new cars was mainly because of their lighter weight.
Take the large single tire model 425/65R22.5 as an example, the weight including the rim is 153Kg each, while the weight of the twin 12R22.5 (including the rim) is 224Kg/each.
A 6×4 tractor can reduce the weight of 284kg after replacing the big single tire. A 6-axle train can reduce the weight of the vehicle by about 0.7 tons in total, which makes a considerable contribution to weight reduction.
Super fuel efficient
Because of the light weight and the smaller contact area with the ground, the rolling resistance and friction of the large single tire are much smaller than that of the twin tires, which has the characteristics of fuel saving.
The Society of Automotive Engineers (SAE) conducted related experiments in 2005. A truck with a large single tire can save up to 12% of fuel on highways; even on suburban road conditions, it can still improve fuel economy by 10%.
Compared with the form of twins, although the big single tire seems to be “all alone”, it is unambiguous in terms of durability.
First of all, large single tires are more than 20 layers, while ordinary tires are mostly 16 or 18 layers. The more layers, the more durable.
Secondly, the heat dissipation performance of a large single tire is much better than that of a twin tire. Especially in the hot summer, a large single tire can reduce the probability of spontaneous combustion of the tire to a certain extent and improve the safety at high speeds.
The other is the cost. For ordinary tires of the same brand and the same “three packs”, the combined price of two tires is slightly more expensive than that of a large single tire.
What you save is what you earn. The operating costs saved by long-term use of a large single tire can be seen as part of the profit.
China is the country with the most toll roads in the world. In order to avoid paying high tolls, truck drivers have been adhering to the driving philosophy of never using highways if they can use national or provincial roads.
However, whether it is in disrepair for a long time or the “tofu dregs project”, the worrisome road conditions of the national and provincial roads will always bring greater load to the tires.
After the tire is worn excessively, the risk of a tire blowout also increases.
If a tire with twin tires has a puncture, you can continue to drive to the repair point. If you have a large single tire, you must get out of the vehicle for repair immediately, otherwise you cannot continue to move forward.
If equipped with automatic inflation equipment, the cost will increase substantially.
Taking into account such emergencies, the practicality of large single tires is largely compromised. If the location of a puncture occurs on a highway, its risk will be further increased.
It is not easy to save fuel
Bad road conditions will not only reduce the life of the tire, but also weaken the advantages of the big single tire itself.
The Oak Ridge National Laboratory in the United States has done experiments with large single tires under comprehensive road conditions. They let a car drive along western Michigan to Portland, Oregon.
The whole process experienced various terrains, various weather changes and varying degrees of traffic jams. In the end, it only saved 2.9% of fuel compared to the twin-tire model, which was very different from the performance under good road conditions.
Also because of toll fees, the frequency of high-speed trucks in China is much lower than that in foreign countries.
Due to long-term driving on ordinary roads, a large single tire will not be able to give full play to its advantage in fuel economy.
At present, there are not many domestic manufacturers that can produce large single tires, and there are very few large single tires with high cost performance, and sometimes they cannot buy the models they need.
In addition, manufacturers have strict regulations on the rated load of large single tires, and the overload space is relatively small.
Of course, overloading will not only suffer unnecessary fines, but also risk your own life.
“National conditions” is an important factor in determining whether a product has a market. Even though large single tires have many bright spots and advantages, they still cannot flex their muscles in the face of China’s special road conditions and transportation environment.