Wheel & Tyre Sizes

[bikemonster]

Hi All

In the rest of the car world, the generally accepted wisdom is that handling improves when lower profile tyres are fitted (at the expense of a harsher ride).

And yet everybody seems to agree that Sevens handle better with smaller wheels and taller tyres (for a given tyre width).

My question is this: what makes Sevens different? I am not disputing the assertion that smaller, taller tyres are better for handling/grip, I just want to know WHY.

Thanks in advance.

monster

[Shaun_E]

I'm not convinced that lower profile tyres do improve handling. Larger wheels are fitted normally to accomodate larger brakes and then lower profile tyres are required to fit under arches/keep gearing the same.
In a Seven, the car is so light that huge brakes are not required and a very good braking setup can be accomodated inside a 13" wheel. Small wheels are lighter than large ones, reducing unsprung weight and rotational inertia which improves the ride and the "handling".
The other reason for using 13" wheels on a Seven is that there is a good range of track tyres available for them.

[jimmyslr]

Also, tyres are just another part of the springing/damping equation. A deeper sidewall acts as a softer set-up than a thin one, something that is compensated for in the actual springs and dampers. I believe therefore that one option is not good or bad, but that they all have to work together.

The key though i think is the point above re unsprung weight and, historically, tyre size availability.

[jezzer]

Totally agree with the above comments, the majority of the time, larger wheels are fitted to allow larger barake discs and callipers. I know from experience, that depending on car, the larger the wheels do not definitively give better grip, and certainly give worse ride but for most people all of the above is irrelevant, it is how the car looks that makes people change to larger wheels!IMO!