Page 57 - RB-65-13-2

RETYRE
purposes of SME’s and therefore extremely useful to meet the Federation’s goals.
Now, BIPAVER has finished WP1 – which is not entirely equal to Step 1 – but nervertheless this gave BIPAVER the all-important “Go” decision at the end of March. BIPAVER can therefore now show some results and findings. Unfortunately, in line with the outline of the programme, BIPAVER cannot yet share these detailed results as the intellectual properties currently with the members of the consortium.
The successful measurements and analysis of rolling resistance - influence between new tyre and casing in relation to tyre/casing age - showed that the rolling resistance coefficient CR at an ambient Temperature of 25°C behaves relatively constant over the tyre/casing age and is unaffected by tyre size, make and age. The share of the casing has been found at around 50 per cent in reference to the overall tyre rolling resistance. Based on this correlation the Milestone was finalised with a “Go” decision from the Project Steering Committee on March 22nd 2013.
Although earlier studies (e.g. BAST study about the noise emissions of retreaded tyres in comparison to new tyres) and experiences indicated that noise and wet grip is not affected by make or age of the casing (in line with the results for rolling resistance), it has been decided to underline this impression by a scientifically proven analysis. The measurements comprise all tyres, new and used, buffed at 2 mm above the breaker. The red line represents the background noise.
In order to assure the validity of the results three tyre sizes have been selected that are dominant and representative for the European Retread Market: 385/65 R 22.5
Strongest tyre size for new and retreaded tyres in Europe; Representing the trailer application
315/80 R 22.5
Second strongest tyre size for new and retreaded tyres in Europe. Representing the drive axle application
275/70 R 22.5
Dominant tyre size in Europe for public transportation and therefore sensitive regarding rolling noise (mainly urban traffic) and Wet Grip (Safety).
A selection of the most relevant tyre/casing makes divided in four classes of age (new, 2, 3 and 4 years of age) have been made for all three tyre sizes.
All these tyres will be retreaded using one single tread and applying the same production parameters per tyre size and afterwards compared individually regarding their noise and wet grip performance (in compliance with UN-ECE R117 specifications).
Finally, the influence of the casing make and age will be demonstrated. With the successful evaluation of these measurements, WP1 will completed and finalised. The project will then continue with the analysis of the influence of the production parameters in the retreading process using a “virtual” standard casing in the major tyre sizes 385/65 and 315/80 R 22.5 (see listing above). Also the influence of the dominant retreading processes (mould cure (a.k.a. Hot) and pre-cure process) will be examined.
In general the use of truck tyres
is well and commonly known. Especially in the field of international traffic one is familiar with tyres in their haulage application, both in steering and drive axle applications. However, the particular field of the use of commercial tyres in urban applications needs clarification, since this use impacts upon the mileage, therefore the economical use and is regarded as severe.
Retreading has two traditional application segments in which the appearance of retreaded tyres is even more important than the average share of