Fat Tyres on MB RIMS on an SLR Type Query!

[Krismuss]

My new 7 runs 7.5" MBs front and 8.5" MBs rear, shod with 215/50 & 235/45 Kumho V70s.

 

However, is this sensible for road and track day use or 'over tyred'.

 

My spare wheels are all 6" front & 7" rear (minators) so they'll be shod with slicks or used CR500s.

 

Checking Yokohama's details it looks like 175/55 (front) and 205/55 (rear) will fit the large MB rims (just), though again is this ideal or am I better sticking with the fat kumhos?

 

I'm happy to stick with the kumhos as is though the MB wheels will be day to day use rather than track use (when I'll stick on the slicks or old CRs).

 

Any advice and experience of these size rims & tyres appreciated.

 

Thanks

 

Chris

[Shaun_E]

That's the common set-up for class 4, 5 and 6 in the L7C sprint championship. These are 190bhp + cars (class 4), unlimited in class 5 and mostly Hayabusa in 6 so all pretty powerful. The fat fronts appear to provide better braking although there isn't lots of evidence. In a high power car on track they are certainly not over tyred but it depends what you want out of your car - ultimate grip or a car that moves around more.

I run this set-up for sprint/hillclimb, road and track and just have a harder compound set for track. My car has a 260bhp Duratec.

[Krismuss]

Thanks Shaun, very useful to know

 

Best look out for a spare set of 8" wheels then...

 

[A10ROX]

Sprinters tend to add more rubber than Circuiters(if that's a term)

 

In very general terms ...

More rubber more contact

More contact more resistance

So it is a compromise

 

You later sizes are more in keeping with R400+ (incSLR) for road or track use

[Simon.Rogers1]

My data shows no corner force increase with the wider fronts but under hard braking the wider fronts clearly give 0.3g increase.