Obtuse Tyre Sizes

Tyres can come in all shapes and sizes. From your normal 205/55 R16 to the mahoosive 285/40 R22 and all the numbers in between. But, there are a few select vehicles out there that don't follow the standard system.

But first, what do these numbers mean? Well, the 205 is for the approximate width of the tyre in mm. 55 is the profile (the height of the tyre) and is represented in a percentage format. So, this would mean the height of the tyre is 55% of the width; approximately 112.75mm. Whilst the R16 is the radius of the tyre in inches.

A bit complex eh? Well, thankfully you won't need to measure these! It's printed directly on the side of the tyre so when you call in, just state the numbers and awaaaay we go!

Back to the odd tyres sizes. Now, you've probably seen on most rear wheel drive and performance vehicles that the front tyres are small than the rear. For example, the Jaguar F-Type SVR has 265/35 R20 on the front and 305/30 R20 on the rear. But, why is this? When you have a rear wheel drive vehicle, all the power will be sent to the rear (unless it's a newfangled BMW that can send 100% of its power to the front or rear). Now, unless you have an elephant sitting in the boot, there will be no weight to help squish these tyres to the floor and provide grip. Having wider tyres helps to increase the grip and provides better traction to the road.

But why don't performance FWD vehicles such as the new Type-R, Megan RS or Golf GTi have larger tyres on the front? Oversteer. Oversteer! Having too much grip on the front and not enough on the rear can result in an unexpected drift around a corner or a complete spin out. Not helpful when going around a roundabout.

However, this didn't stop the folks at Audi from testing it out on the RS3 (from 2011-2015). The front tyres were 255/30 R19 where the rears were 225/35 R19! If you spot one of these in the wild, they are quite rare so keep an eye out, you know what to look for!

Other noticeable examples of weird/unique tyre sizes include the Lamborghini Countach with 205/50 R15 on the front and an insane 345/35 R15 on the rear. Just imagine how wide that is!

Or, going the other way and increasing the rim size to keep the rolling radius correct, we have the Plymoth Prowler with 225/45 R17 on the front and 295/40 R20 on the rear.