Stars vs. Plies: What’s the Real Difference for OTR Tyres?
Finding the correct size is merely one part of getting the right rubber for your heavy vehicle; the other depends on understanding the "muscle" inside the casing. You're not alone if you've looked at a sidewall and wondered why one tyre has a Star rating while another carries a Ply rating. While they speak different languages, both evaluate the structural strength of an industrial tyre. Here is the real-world breakdown of how these ratings impact your fleet’s performance. The Traditional Workhorse: Ply Rating (PR) When we talk about an OTR bias tyre , we’re talking about a classic, cross-layered construction. Historically, the "Ply Rating" told you exactly how many layers of cotton or nylon cord were inside the carcass. Today, with high-strength synthetic materials, we use fewer physical layers, but the "PR" remains the standard measure of carcass strength . A 28-ply or 40-ply rating is a badge of toughness. These tyres are the kings of "cut-a...