Cross Ply Tyres

What do the numbers mean?

Crossply tyres have the simplest of all tyre sizing systems. If we take a 640-15, for example, this has a section width of roughly 6.4 inches and fits a rim diameter of 15 inches. 

Occasionally you’ll spot a letter inserted between the numbers on crossply descriptions like this: 820H15. The H indicates the speed rating, in this case it is 130MPH.

What no profile?

Unlike a radial tyre, a crossply tyre typically doesn’t advertise its profile (sidewall height) in the size description. Crossply sidewalls are mostly the same height as the tyre is wide (between 96 and 100 per cent). For comparison, the tallest radial has an 80 per cent sidewall height.

What is a crossply anyway?

The cords in the fabric used in the plies of a crossply tyre are positioned around 45 degrees to the direction of tyre travel. Crossply construction can see the plies vary up to ten degrees either side of the 45-degree mark depending on the application.

Crossplies are awful, why would I want another set?

Crossply tyres have unfairly been given a bad reputation for handling irregularities. That’s because most people have only driven on ancient crossply tyres that are fit only for the scrap pile. Fit a fresh set of crossply tyres and your car will be transformed.

Don’t be fooled by the bloke in the pub/forum/show who declares that switching to radials is the best option – it really isn’t. In many cases the surest way to ruin a great car is to switch to radials. The manufacturers knew what they were doing, and we’d go with their R&D knowledge over the club know-it-all any day.

There are exceptions of course. Cars on the cusp of the radial revolution like the Mini and E-type both started out on crossplies, but many are now on radials.

And some crossply sizes feature a radial-construction version, the 550R16 and the 670R16, for example. This means you get the looks of a crossply with the additional road-holding benefits of a radial.

Can I use radial and crossply tyres on the same car?

Arcane legislation allows (incredibly) the use of radials at the rear and crossplies at the front. Never the other way round and never on the same axle. 

We’ll add another ‘never’ to that list: Never mix radials and crossplies on any vehicle regardless of what the law says. The tyres have very different handling characteristics and you are asking for trouble if you do it.