Tyre profiles

[Drumster]

I'm currently running on 15" rims and 195/50 tyres and I am thinking of changing the wheels and tyres,primarily to ditch the Michelin Pilots. I would also like to keep the same road height (having never clouted the sump to date). Therefore is there any adv/disadv in going for 14x6" with 185/60 or 13x6" with 185/70? I am assuming that either combination will keep the ride height approx the same, or have I got this completely wrong?

 

Chris Alston

[Peter Carmichael]

Tyre profiles are somewhat nominal.

 

Supposedly, the sidewall height is the tread width multiplied by the profile percentage. Nominally, you would be going from tyre diameter:

 

15*25.4 + 2* 195*.50 = 576 mm 22.7 inches

 

to

 

14*25.4 + 2* 185*.60 = 577.6mm

 

or

 

13*25.4 + 2 * 185*.70 = 589.2mm

 

[WILL FLY]

The quoted figure from Yoko for A032Rs are :

 

15 inch 195/55 = 593 (They don't do a 50 profile in 195)

 

14 inch 195/60 = 591

 

13 inch 195/70 = ??? (They don't fo one)

 

For comparison :

 

14 inch 185/60 = 583

 

14 inch 195/60 = 591

 

13 inch 185/70 = ??? They don't do one

 

13 inch 185/60 = 552

 

13 inch 205/60 = 578

 

The best you can do in 13 inch is the 205/60 at 578 or you can go 14 inch and get a 195/60 at 591.

 

I personally use 185/60R14 which has a diameter or 583.

 

If you look at the difference between the 195 and the 185 14 inch it's about the thickness of the tread, which makes it hardly worth bothering about.

 

I don't know about other sizes but 185/60 R 14 A032Rs from George Polley are 61 quid each inc VAT adn P & P or fitting if you go to heathfield.

 

I got 5 tyres fitted for 20 quid.

 

[CHRIS CLARK]

13" x 185 or 205/60's (AO21's) work out at approx. 50 UKP + VAT from GP.

 

My 'Prisoner' 15" use Yoko 520's.

[Drumster]

Thanks for your replies.

 

I'll probably go for Yoko 21Rs, but I guess my real question is that given that ride heights are v. similar what is the better tyre/wheel combination 185/60 on 14" or 185/70 on 13". The car will mainly be used on the road with occasional trackdays in mind. I think ideally I would like to go 13" and 185/60 but am concerned about lowering the ride height to much.

 

Any comments much appreciated.

 

Chris Alston

[murph7355]

I did a similar swap last year, going from 185/60/14 Michelin Pilots to 185/60/13 (front) Yoko 21Rs (I have 205 rears).

 

I've not found ground clearance a massive problem. I have to be a bit more circumspect on speed bumps etc. but generally it's OK.

 

Unfortunately I changed a couple of things at once so it's hard to say what gave the biggest change (though the change was absolutely positive) between the tyres or the smaller (and much lighter) wheels.

 

My guess is that tyres make the biggest difference, especially moving from the Pilots, which are absolutely terrible in everything apart from wear rate, with a smaller but still noticeable difference in moving down a wheel size (or two in your case).

 

My car gets used more on road than track (and for long distances at times) and the 13"s are fine, so you won't go wrong moving to this combination. You'll probably find the wheels and tyres are also cheaper too which is always a bonus, especially as the 21Rs will wear out much quicker than the Pilots.

 

 

C7 AJM

 

Edited by - Andy Murphy on 13 Feb 2001 10:14:05