Nonsense! My rims are 18x8 front and 18x9 rear and I just use same 245/40/18 on all 4! Tire size also got range if fitment possible so like 245 can fit for 8-9.5jj width.

TR1 btw some say ok but I have also heard bad comments on it saying the grip is not good, so not sure.

Not really, it looks more square while the rear will look more rounded. Anyway it still works perfectly fine, no issues whatsoever, so people who say must use staggered tire sizes are incorrect. Basically for my 8jj at the front, I can run 225/235/245 while my 9jj at the rear can run 235/245/255/265 so there are 2 sizes overlapped which can be used for all. Of course running staggered sizes vs all same will give some different handling behaviour. Smaller fronts will make more understeer while all same will be more neutral handling or sharper front end bite.

I was talking in relativity, so smaller fronts will be relatively more understeer than all same sizes. I have tried both tire setups on my staggered rims.

No, I never rotate them, will look ugly and might not fit that width to the front also. I am actually looking to change back to all same sizes rims now so I can rotate.

What sensors?? Often they just talk only coz they don't know how to explain and just take the easy way out.

As he mentioned above if change width also need to consider the sidewall height because 245/40 is taller than 235/40 but less than 235/45. What are your actual sizes now? (Sorry if already mentioned before, I might not notice it).

This post has been edited by 6UE5T: Sep 11 2020, 11:45 AM

No probs, glad to be of any help.

Ya very unbalanced combo. The front is way too small in rolling diameter, very thin profile, while the rear is very tall sidewall! Difference in sidewall height is a massive 2cm! Your car must be low at nose while the rear sticking up, and the fender gaps at the front is much bigger too. Stock Merc C class should not be like that. Are you sure they're not 225/45/18 and 245/40/18??

Ah ok, my staggered sizes also last time were the same. Then I'd suggest you use 245/40/18 all around for better traction and slightly sharper front end turn in. But in order to rotate you'd still need to dismantle the tires from the rims to switch them because your rims are staggered sizes, so still not as convenient.

Another thing to check is what are your exact rims width? If the front is only 7.5jj then you can only fit 225 tires and cannot fit 245. You need minimum 8jj width to fit 245.

I don't know C class rims width. If BMW F30 328i/330 MSport, they also come with staggered rims size 18x8jj/8.5jj with stock fitment 225/45/18 and 255/40/18. The non sport model comes with all same 18x8jj rims with 225/45/18 only.

Some people just swallow just whatever SC tell them even without proper proof or explanation, easy meat to get con by workshops.

Yeah I also suspect as such, so max can only go 235/45 but will be about 0.5cm taller sidewall, will be slightly heavier but more comfortable. Handling might be slightly more neutral but not much noticeable if just normal driving.

235/40 is 0.5cm thinner profile than 245/40 and 0.8cm thinner than 225/45 so you will feel noticeably harsher ride/less comfortable. Will look uglier as well coz fender gaps increased by as much. I personally wouldn't use that.