What tires sizes?

[Tmason]

275/35/20 front 305/35/20 rear
285/35/20 front 305/35/20 rear
285/35/20 front 315/35/20 rear

I'm getting a set of 6gr wheels and can't decide which size tires to go with. I'm leaning towards the new continental extreme contact sports. All these sizes are similar in price just not sure what combo to go with.

I'm lowered on bmr springs which is 1.2 front and .5 rear so I believe all should be fine and not rub.

Any opinions? Car will be mainly a sunny day spirited driver with maybe a little track time.

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[JohnD]

Here's my personal opinion.

The PP was set up by Ford with a specific combination of springs, shocks, sway bars and wheel/tire sizes to produce a bit of understeer under steady state cornering at the limit of adhesion. Steady state means neutral throttle. The reason being that understeer is easily managed and people are less likely to kill themselves with an oversteering monster that has more front tire grip than the suspension was designed for.

So unless you are a very experienced driver with lightning reflexes and tons of track time in a loose car, you should probably not stray far with the tire size difference front and rear. Stock being 255/275 so keep it at 20 mm difference front and rear, so 285 front 305 rear. That's what I did, and while the overall grip is better, it still retains the balance Ford intended it to have and has no tendency to snap oversteer. It's a very forgiving car and unless grossly overdriven into the corner, the bit of understeer it has is easy to manage. And you can still induce all the oversteer you want with your right foot on exit.

Of course if you're building a car for serious track or competition use and you are a very experienced track driver, that all goes out the window and you set it up for your driving style.