Contact patch on A048s

[Alias]

I've been running 195/60/14s for a couple of years now. I've recently done an airfield day where I was pushing the car quite hard, but was losing traction on the rear. I've since had a look and my contact patch isn't quite what it should be.

 

Inside edges (both rears) contact patch starts 15mm from the edge of the tyre

Outside edges (both rears) contact patch starts 20mm from the edge of the tyre.

 

Consequently, despite the tyres being 195mm wide, my contact patch width is 160mm.

 

Is this normal? Before I get asked the obvious - I'm running the tyres on 16PSI.

 

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1800 Supersport with 6 gears and clamshell wings.

[Myles]

How wide are the rims?

 

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[simonbell]

Which dedion ears are you running?

 

Is your dedion tube bent or are the shock mountings cracked?

 

Simon Bell - Caterham 7 Duratec R

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[Alias]

Rims are 185 (I believe) so I've slightly stretched the tyre onto the wheel.

 

I would have thought that if the DeDion tube was bent then I would have uneven wear. Am very happy to be corrected on this. Shock mountings are fine.

 

Not sure what ears I've got, I'm presuming the std ears for a 1995 De Dion Car. I was thinking that if I had the ears which provided more camber, this would provide even less contact patch on the outside of the tyre.

 

It's like this even when the tyres are cold, so don't think it's due to the tyres heating up when on track.

 

Stewart you may be right that my pressure gauge is inaccurate. I've got an accurate digital one too, so I'll cross-check

 

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1800 Supersport with 6 gears and clamshell wings.

[Jason Plato]

you sure the tyres are not 205 width on a 6" wide rim

 

 

 

here is C7 TOP

South Wales AO

[The Polisher]

Rob,

I assumed that this was a normal feature of 48's.

My front 185/60/14's on 6" rims have a 130mm conact width and my rear 205/60/13's on 7" rims have a contact width of 150mm. Both are much less than the tyre tread width running at 15/16 psi.

I assume that the 'wasted' tread comes into play when cornering and accounts for the progressive nature of the tyre when on the limit.

 

 

Dave H.

Mad about S77ENS

[Alias]

Dave J - they're definitely 196 x 60 x 14s.

 

Wheels are 6'' as you rightly note.

 

Dave H, If you find A048s are progressive then you've got a much better feel for the car than I have. ☹️ However, I'm pleased to note that I'm not the only one with this smaller contact patch.

 

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1800 Supersport with 6 gears and clamshell wings.