Tyres

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le tigre
Posts: 25
Joined: Tue May 14, 2013 11:02 am
Location: S.W.France

Tyres

Post by le tigre » Tue May 08, 2018 10:09 am

Hi all. The time has come to replace my tyres which although they have reasonable tread are now 11years old, so time to change. I have looked back through the forum and although this has cropped up previously I really wanted some recommendations from anyone who has recently replaced their tyres and how they rate them. I have 6x15 Minilites on the front with 185/55 R15 Pirelli P6000 and 7x15 Minilites on the rear with 195/50 R15 Pirelli P6000s I am not sure why the profiles are different front and rear as I didn't put them on. Does anyone have any ideas on that ? I already have clearance issues with the inner wings at the rear and have reduced the lip as much as possible. Would going up to 55s at the rear help or make it worse?
I would be really grateful for any suggestions for tyres that are good all round but also good for the odd track session.
Many thanks in advance.
Andy

Adam
Posts: 18
Joined: Thu Nov 24, 2016 5:19 pm
Location: Lincolnshire

Post by Adam » Fri May 25, 2018 1:22 pm

I imagine the different profiles were chosen because the section widths are different. The profile, or more correctly, the aspect ratio, is a percentage of the section width, which is given in millimetres. IE, 195mm*50% on a 15inch diameter wheel, which happens to be 7" wide. 185/55 should therefore be 3mm taller than 195/50.

The other factors that matter are the load and speed index.

The key thing to consider is the tyre rolling radius, because that will affect the gearing of the car and also the speedo accuracy. going to a lower aspect ratio, with the same section width will mean a smaller tyre that may clear the arches better, but will also give a lower gear ratio. I don`t have a tyre data book to hand, but a decent tyre fitter will be able to look up the tyre rolling radius for you, or you can probably find it online. Or speak to Dougal Cawley at Longstone tyres, they specialise in vintage and classic stuff and give good advice. Good info on their website too.

My car has 14" Minilites with 185/70-14 radials fitted. When I got the car it was on some tired old 165-14s. I did have a problem with the front tyres rubbing inside the arches when I went through a dip. But the front ride height was low because the springs had weakened with age. I rebuilt the front suspension with new (heavy duty) springs, new bushings and dampers and now there is no rubbing at all. The steering is lighter too because the geometry is where it is meant to be.

Hope this helps.
Adam Moody

le tigre
Posts: 25
Joined: Tue May 14, 2013 11:02 am
Location: S.W.France

Post by le tigre » Mon May 28, 2018 10:39 am

Thanks Adam,

Very useful.

Andy

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