Question on choice of tyre width.

saitrix

saitrix

saitrix

Soldato
Joined
2 Jun 2003
Posts
8,950
Location
Nottingham
Hi,

My car comes with 13x5.5 alloys as standard, with 175/70 tyres. Now when I come to put new rubber on there would I gain more grip from using 185/60's instead? I don't care about the change in rolling radius as I don't use my speedo at all.

See my situation is I can get the tyres I want in both 175/70 and 185/60 with such a small difference in price it isn't a factor. What would be best for the greatest grip in both wet and dry?
 
Wider tyre = greater grip

Switching down from a 70 profile to a 60 would probably aid grip a bit more too as there will be less flex in the sidewall.
 
Well I thought that too at first. But as you increase the width of the tyre, the contact area the tyre has is wider, but because of the same weight the length of the contact area should be shorter. See as the car weighs the same with both tyre widths, the 175 will 'squash' the tyre more (assuming same tyre pressures are used) than the 185 one. I couldn't work out at what ratio the difference would be so I couldn't work out what the change in contact patch would be.

Aye less sidewall flex would be nice really as 70 profile really is quite large. Just to mix it up, right now I am using 185/70's which are huge sidewalls. Hmm that's another point, with the smaller sidewall that also helps resist against 'squash' in the 185 wide tyres. Hmm, I hate tyre choices.
 
Yeah lower profile = less sidewall rollage but harsher over uneven roads.

Wider tyre = more grip but doesn't turn in as well when cornering hard. (ime in going from 215/40/16 to 195/55/15)
 
Decided to go for the same size as penski suggested, 175/60 but keep on 13x5.5. ;) £38 for Yoko A539's, can't complain!
 
Just used an online tyre size calc too and it came out with my new tyres are going to have a 1" smaller sidewall! Should be nice and stiff. :D
 
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