I just swapped the summer tires on and realized that the roads are in pretty awful condition. This is nothing uncommon, the registration tax for my FS was in excess of €300k when new (on top of the purchase price of the car) and the government likes to use money to bribe voters with social security benefits instead of keeping the roads in decent shape so there's no bang for the buck to speak of. Only 12% of registration/car/vehicle/fuel tax revenue is spent on road maintenance.

As the tires are due for replacement some time this summer, I've started wondering if going with a higher profile tire, 275/40R21 instead of 35, would work. The speedo will be approximately 4% off which isn't a big deal, but I'd get at least slightly more clearance between all the potholes and the wheels.

I'm not planning to buy new wheels (20" would certainly help, with 40 or 45 profile tires) so it's all about what I can do with the current ones. All input is much appreciated.

 

wait... when purchasing the car you had to pay 300k euro of "registration" tax????

 

When new, yes. I imported mine from Germany second hand so the tax was substantially reduced. Still not cheap, but there's nothing much you can do. Except to drive a Kia or equivalent $#!%box and suffer like a proper subject of a welfare state...

 

Conclusion: 275/40R21 does fit. The margins are slim, approximately a quarter of an inch to front knuckles and the rubber flap in the rear of the doorsill touches the tire during installation but when the car is on its wheels, everything is perfectly fine.

I just had new tires installed. Continental PremiumContact 7 in this size. The ride is considerably smoother than with 35-profile Pirelli SportMaxx, tire noise is reduced and they grip great. I haven't had a chance to push them to their limits on the dry yet, they should be pretty much on par with Michelin Pilot Sport, but in the rain they're nothing short of phenomenal. They also track well, which has further been improved by the polyurethane bushing upgrade we did recently.

I probably wouldn't choose them for a Supersport as the steering isn't quite as razor-sharp as with some other high performance tires, but for the Flying Spur Speed they seem to be a fantastic combination.

Potholes? A thump. Not a crash anymore. It's amazing what 5% more profile does.

 

I have some after market 20 inch wheels, I went thru a lot of tires in the front. First I had 255 30 20s and they kept popping from potholes or having 4 people in my car lol. Then I had 255 35 20s never had an issue had them till they wore out. This time around I put 255 40 20s and the car just feels heavier for some reason. The ride is smoother tho. I would say the 255 35s were the best overall fit for me. This is the car with the 255 40 20s right now

 

Personally I prefer to have some flexibility in the sidewall of the tire and as much control in the suspension geometry and control arms as possible. Hence 90 shore polyurethane bushings that keep the alignment virtually perfect throughout the suspension travel and under load, and just enough smoothness in the tires to make transition between static and dynamic friction progressive and predictable instead of the other way around.

On the other hand my driving habits aren't by far the most socially acceptable. There's something inherently in driving what most people perceive as a luxobarge like a tarmac rally car. The Spur has proven to be a fantastically capable 2.5ton+ hunk of steel and humiliating even moderately well driven Porsches and Ferraris isn't out of the question at all. And to clarify, I don't mean in straight line.