Taller tyres for 20" wheels on W213?

[bantamug]

Couldn't find an obvious answer in the pinned threads: I'm considering buying a W213 that's got 20" wheels on it with run flat 245/35's on the front and 275/30's on the rear.

I've never gotten on with run flats so would look to replace them with regular tyres in a like for like size.

Does anybody know if / how much wiggle room I'd have to install "taller" tyres to improve the ride a bit? e.g. 245/40s on the front (~13mm difference in diameter) and maybe 275/35s on the rear (~14mm difference) - ideally don't want to be changing wheels if I can avoid it.

Thanks!

 

[renault12ts]

The diameter would be 24.5mm greater, not 13mm...and 27.5mm on the rear.

 

[Gbrowncls55]

The speedo would also be incorrect. Under reading

 

[bantamug]

The diameter would be 24.5mm greater, not 13mm...and 27.5mm on the rear.

Ah yes, I clearly can't double.

Speedo reading seems manageable - I'd be ~3-4% out?

More concerned about physical clearance and front tyres rubbing on vehicle when turning etc. 2-3cm larger overall diameter doesn't seem like a deal breaker, or am I being optimistic?

 

[Smiley]

The larger wheels can be a real pita on our roads - very harsh ride compounded by the run flats and problems with cracked wheels from pot holes. MB seems to think that everyone wants bigger and bigger wheels. The best long term solution is to find out what the smaller rim sizes are for the car and get a new set of wheels / tyres + sell the 20s.

 

[Gazwould]

Taller tyres on 20 " won't be much help as the biggest physics at play for ride quality is overall wheel weight .

A taller tyre might not even measure right in the real world compared to the online wheel and tyre calculators .

Drop a size or two according to the Merc recommendations .

 

[Stratman]

Ah yes, I clearly can't double.

Speedo reading seems manageable - I'd be ~3-4% out?

More concerned about physical clearance and front tyres rubbing on vehicle when turning etc. 2-3cm larger overall diameter doesn't seem like a deal breaker, or am I being optimistic?

You speedo would be under reading which is illegal. The permitted tolerance is all in the over reading direction.

 

[ALFAitalia]

If it's just 3 or 4 percent he probably wont be under reading. From the factory most cars over read by a few percent. Its done deliberately to avoid selling cars that under read...which is illegal. My CLK under read by nearly 10 mph at a GPS verified 90 mph!

 

[renault12ts]

Mine under reads by fewer than 3 mph at 50 mph.

 

[ALFAitalia]

Obviously I meant over read by that much at 90...not under. Why is this the only car forum I go on that you can't edit posts 1for very long?..very annoying !