Bigger Tyres on 20inch e class turbine alloys

[Osca]

Hi , I have an e class premium plus with 20inch turbine alloys. Went to the tyre shop because my alloy wheels cracked . The guy in the shop is insisting I change the tyres to a thicker size like 275/45/20 to prevent my new alloys from cracking again .

My question is will I encounter any problems like handling or else if I were to do this ?

Currently I’m using 275/30/20 at the back and 245 /35/20 at the front

 

[MCFastybloke]

Thats a bad piece of advice.

The rolling radius is 259mm different

Put sizes in here Alloy Wheel & Tyre Fitment Calculator. Offset, Tyre Stretch and Speedo Error | Will They Fit and you will see

 

[Smiley]

The tyre guy is right and wrong. He's right that a "thicker" tyre ie one with a bigger sidewall will help to protect the (oversized and impractical) rims from damage - but he is wrong to suggest simply taking the same width tyre and putting a larger sidewall.
The correct way to achieve a larger sidewall and maintain the overall tyre diameter (and thereby not upsetting the handling) is pretty blindingly obvious really.....you need to reduce the size of the rims down to 19s or 18s.
If you enjoy spending lots of time at the tyre shop and getting wheels welded then stick to the 20s; otherwise get some 19s or 18s in the correct specs for your car.

 

[ALFAitalia]

The rolling radius is 259mm different

I don't think you meant that!!!....The diameter is 55mm bigger...the radius is half that at 27.5mm. The whole car would sit over an inch higher....not a great look....and that's assuming the tyres did not hit anything.