REPLACEMENT TYRE

Perhaps the main reason for the widespread acceptance of polybutadiene rubbers arose when it was found that they gave a vastly reduced tendency for the circumferential cracking at the base of tyre tread grooves with crossply tyres when used in blends with SBR. With crossply tyres now replaced by radial tyres, this factor is no longer of great importance but the rubbers continue to be used because of the improved tread wear and good low-temperatue behaviour imparted by their use. 

A thin rubber sheet applied in the replacement of the sidewall pattern details in the retreading of pneumatic tyres. A similar film of rubber specially compounded to resist oxygen or ozone or to prevent the migration of carbon black into a lighter rubber, e.g., a tyre white sidewall. 

Styrene butadiene rubber (SBR) is, quantitatively, the most important synthetic rubber. It is a copolymer of styrene and butadiene in such a ratio that its rubbery nature predominates, vulcanization is carried out with sulphur, reinforcement with carbon black. It is used at a very large scale in tyres for passenger cars, thanks to its excellent combination of abrasion resistance and friction on the road. In large tyres it can not replace natural rubber because of its heat development (hysteresis losses). 

In a further work, Tang and Curtis26 have studied the influence of the tyre components by replacing coal with model compounds 4-(l-naphthylmethyl)-bibenzyl (NMBB), dibenzothiophene and 5-methyl-8-(l-methylethyl)dibenzo-thiophen-4-ol (MMDH). Carbon black was active for the NMBB hydrocracking, whereas little activity was found with SBR, waste tyres and waste tyre liquefaction residues. However, when the latter residues were previously heat treated to remove organic coatings and recover the carbon black component, significant NMBB conversions were observed. Moreover, both carbon black and heat-treated residues were active for the hydrodesulfurization of dibenzothiophene and MMDH, particularly when combined with Mo naphthenate and S. These results confirm the catalytic properties of carbon black in coal-tyre coliquefaction, provided that its surface area is accessible. 

The tyre is worn or charged improperly. Charge the tyre to the proper pressure or replace the tyre. 

Left-right swing/up-down bounce The tyre is charged improperly The stabilizer bar is bend or damaged The vibration damper is worn Charge the tyre to the proper pressure Replace the stabilizer bar Replace the vibration damper... 

The tyre is worn or is charged improperly Replace the tyre or charge it to the proper... 

The pavement surface characteristics affect not only driving safety and comfort but also the environmental pollution (mainly noise) and the vehicle operating cost (maintenance cost, tyre replacement cost, wasted fuel cost). 

The synthetic rubber industry has never looked back and by the 1960s had overtaken NR in terms of production and usage (Table 4.1). At one stage, it was predicted that SBR could eventually replace NR as an industrial elastomer, in particular in tyre manufacturing. However, that prediction never materialized because NR is still needed to provide the required sturdiness and heat resistance in tyre performance. Radial tyres are typically made up of nearly 50% NR whereas aviation tyres require 100% NR in their formulations. Now NR and synthetic rubber complement each other in many applications, each with its niche properties. In the present drive towards sustainable development, NR is viewed as a renewable raw material and is gradually regaining its dominant role. 

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