Different brand tyres on same axle = illegal???

[ExFiF]

BMW 3 series is a very common example, same diameter wheels, but different size tyres front and back. Even some quite cooking versions are like this.

[GC8]

Virtually every Porsche since 1989 and every 911 since 1974.

[fourwheelsteer]

The original Citroen DS came with wider front tyres wider than those on the rear. The logic being that the front tyres bore most of the weight, did the driving and most of the braking and steering so needed to be larger to suit their more demanding role. Later DS variants got equal-size tyres all round, presumably because it made life simpler.

I doubt that there is any law or construction and use regulation that specifies that a car cannot have wider tyres at the front (or maybe one was introduced after the demise of the Citroen D-series). There are many sources that recommend fitting the newest/best tyres to the back wheels of a car - any car - but they are guidance rather than law. For some reason oversteer (back tyres losing grip first) is regarded as A Bad Thing. But understeer is perfectly fine...

[shakotan]

mrmr96 said:

PetrolDriver said:

New POD said:

Some one told me it was illegal to have Larger tyres on the front than the back, after I recalled seeing a mini with MG Metro Turbo 13 inch wheels at the front and 10 inch mini-lites at the back.

IIRC the Crossfire has 19" rear / 18" front?

I know off topic, but can't think of any other cars that are similar.

370Z (maybe 350Z)

You cannot mix sizes across an axle.

You can have 20" wheels on the front and 15" wheels on the back if you like, it's not illegal, just 'odd'.

[mrmr96]

doogz said:

It's perfectly legal to have different sized wheels and/or tyres on different axles.

Indeed.

[BertBert]

MoT manual doesn't fail tyres of different load and speed ratings on same axle. Just size and aspect ratio (although 80% and 82% can be counted the same). Apparently there are also 3 incompatible types of tyre - bias belted, cross-ply and radial.
Bert

[98elise]

GC8 said:

Virtually every Porsche since 1989 and every 911 since 1974.

Add to that almost every mid or rear engine sports/supercar since that era.