Hello all,
I would like a bit of clarification on tyre sizes for example 315/70r 22.5 do all tyres of any brand have the same rolling circumference? Can you get ‘bigger’ and ‘smaller’ tyres from this one size? I heard that Michelin tyres are bigger than for example uniroyal? Your comments are much appreciated
JSingh:
Hello all,
I would like a bit of clarification on tyre sizes for example 315/70r 22.5 do all tyres of any brand have the same rolling circumference? Can you get ‘bigger’ and ‘smaller’ tyres from this one size? I heard that Michelin tyres are bigger than for example uniroyal? Your comments are much appreciated
No, a tyre size marking that is the same between two brands will result in a tyre with identical dimensions when new. Here is a breakdown of your tyre size there:
315 - The width of the tyre in MM.
70 - The height of the sidewall of the tyre as a percentage of the width. In this case 220.5mm
R - Denotes a tyre with a Radial construction.
22.5 - the inner circumference of the tyre, the size of wheel it will fit.
You should also have something like
165 - This is the load rating of the tyre and the number has no direct link to the rated maximum load.
W - The speed rating of the tyre. Thats the maximum road speed permitted with that tyre at maximum loading.
E4 - The ECE marking on the tyre to say that the tyre has been tested to and met or passed type approval requirements in the EU.
What you may find, though I doubt it, is that a Michelin tyre will arrive new with a larger tread depth than a Uniroyal. I would assume though that there are standards in place to ensure that all tyres of each size come with a Maximum amount of tread when new and a minimum amount of rubber above the sidewall when worn to the legal limits to ensure a more accurate speedo reading.
Thank you for your reply, I understand the break down of the tyre size but was questioning from people’s experience do they see the overall size of the tyre different between brands the reason being my tyre fitted some uniroyal drive tyres on a truck that had Bridgestones and had said he’s noticed a drop in speed, I had a set of michilins in storage a put it next to another truck tyre both had same amount of tread but the Michelin was standing about an inch or so taller, I’m just curious of course because I was offered a good price for the set of uniroyals and told they’re a good tyre, just trialling it out. Thanks
A quick check of a couple of manufacturers’ technical data sheets does indeed indicate that the diameter and the overall rolling circumference of their tyres not only differ between companies, but also between different pattern treads of the same nominal size.