Tyre Sizes - Grip

IanW1977

Well-known Member
Hi, We have some Alloys on our car which came with 195/65/15 tyres.

Now in the wet the Tyres are pretty poor with loads of wheelspin.

If I changed all 4 to 205/50/15 or 195/55/15 would it give a bit more grip ??
 

montybaber

Well-known Member
Surface area of the tyre has no effect on its frictional characteristics (or so i was taught in Engineering science)
 

IanW1977

Well-known Member
It's a Honda civic - The Tyres I think are Avon.

It's an old Type S (170bhp I think 2lt engine)

Just wondering as might just get 2 new fronts then for now until next payday
 
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FZR400RRSP

Banned
The width is measured in mm
So 195 is 195mm
Going up to 205 is going to give you a whopping 10mm more rubber on the road
IE not worth bothering with.
Any grip, especially wet grip, is dictated by the compound of the rubber (not that tyres actually contain much rubber any more!)
All the tread pattern does is cut through the water and allow that rubber compound to touch Tarmac.
So rather than looking for wider tyres, do some research for standard size brands that work well in the wet.
As an example, changing from michelins to Falkens transformed my BMW in the wet.
No change in tyre size involved.
 
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redaprilia

Active Member
Going for wider tyres on a light weight car will "reduce" the grip in the wet not increase grip !

Goodyear Excellence tyres ( or F1 if available in your size ) will help but ultimately 170bhp + light weight = wheelspin LOL
 

Trollslayer

Distinguished Member
Low profile will allow greater power transfer but that isn't the problem here. They also risk reducing conformance with the road surface so for the same size you may get less grip.
 

FZR400RRSP

Banned
a l e x said:
What do "low profile" tyres add to the equation?
Low profile = less sidewall deformation/flex in cornering, so greater stability.
You could liken it to trying to run around corners in high heels, or flat shoes. ;-)
 

un1eash

Distinguished Member
I'd just try changing tyres, with the current wet/hot weather we're having ive noticed the roads are very slick but my MR2 with 185 14" wheels which is usually a little tail happy in the wet still out performs the Alfa GT with its 215 17" because its on rubbish rubber.
 

lovegroova

Well-known Member
The width is measured in mm
So 195 is 195mm
Going up to 205 is going to give you a whopping 10mm more rubber on the road
IE not worth bothering with.
Any grip, especially wet grip, is dictated by the compound of the rubber (not that tyres actually contain much rubber any more!)
All the tread pattern does is cut through the water and allow that rubber compound to touch Tarmac.
So rather than looking for wider tyres, do some research for standard size brands that work well in the wet.
As an example, changing from michelins to Falkens transformed my BMW in the wet.
No change in tyre size involved.
Actually 20mm more as there are two tyres, and you need to multiply by the length of the contact patch.

Say, the contact patch is 150mm long, with a 195 tyre you have a contact patch area on each tyre of 195x150 = 29250mm2

With a 205 tyre you have 30750mm2

So, for two tyres, you have an extra 3000mm2 of contact patch, or an increase of 5%.

:lesson:

But, you are quite correct that the type of tyre will have a much greater effect than increasing the width.

Additionally, some better throttle/clutch control will help to reduce wheel spin.
 
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IanW1977

Well-known Member
Hey Women ay I can't influence how she drives !!

I'll just have to get some good grippy tyres then
 
Actually 20mm more as there are two tyres, and you need to multiply by the length of the contact patch.

Say, the contact patch is 150mm long, with a 195 tyre you have a contact patch area on each tyre of 195x150 = 29250mm2

With a 205 tyre you have 30750mm2

So, for two tyres, you have an extra 3000mm2 of contact patch, or an increase of 5%.
The 205 tyre will also have a slightly bigger rolling radius, so the contact patch will also be longer . . . probably. . . or maybe not . . .:confused:
 

Trollslayer

Distinguished Member
There is usually a small plate (often on the driver side diir, you can see it when you open the door) with the original fitted sizes.
 

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