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      05-19-2022, 09:45 AM   #13
aerobod
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Drives: Caterham R500, M2-G87, Macan S
Join Date: Mar 2008
Location: Calgary

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Although in general the wider tyre will give more grip, ther may also be other changes needed to actually optimise that grip and keep the most tread in contact with the tarmac. If a different tyre compound and carcass construction is available in a narrower size, it may have as much if not more grip.

As an example, I have run 3 different tyres and two different camber angles on the rear of my Caterham on the track. 195/50-15 RE-71R, 180/530-13 Pirelli slick (equivalent to a 235 wide road tyre) and 235/45-13 AR-1. All tyres have been run at 1.5 degrees rear camber, The AR-1 is currently on and has been changed to 2.7 degrees rear camber.

To get the optimum grip based on maximum tread contact with each tyre, optimum sidewall roll and tread temperature and bearing in mind each rear wheel has approximately 175kg (390 lbs) of load on them, At 1.5 degrees of camber and cold tyres:
195/15-15: 1.25 bar (18PSI)
180/530-13: 1.10 bar (16PSI) - stiff sidewall and moderate tread flexibility
235/45-13: 1.00 bar (14.5PSI) - soft sidewalls but more rigid tread

When I increased camber to 2.7 degrees the 235/45-13 tyre needed 0.90 bar (13.5 PSI) to keep the optimum tread contact, which equates to about 1.30 bar (19PSI) when hot, a pressure I wouldn't want to drop below to avoid popping the bead off the rim.

Bottom line is you may need more camber and a different tyre pressure to optimise use of a wider tyre.
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