It’s about time I get new tires on my SL550. I’d like to go a bit wider in the rear. Is 305 or 315 possible on the stock AMG rims?

I've got 295s. 305s are doable but will stick out a bit.

I'm running 305s and they fit just fine. They don't stick out at all.....

They don't stick out from the groove in the rear bumper? My 295s do. They fit in the fenders fine but stick out a bit from that divot halfway up the rear bumper.

I'm trying to visualize it and it seems as if a 10mm increase in width (305mm means 10mm is moving outwards and 10mm moving inwards) wouldn't cause a bulge past the fender. It's only 4/10 of an inch.

It won't stick out past the fender if you have stock rims. The fitment will be close to flush with it,

I took a cloth tape measure out to the tire and attempted to measure the distance between the sidewall and the top of the fender lip - it's roughly 1.5 inches (or roughly 38mm) - perhaps a bit less. There isn't much of a change in depth between the fender lip and the top of the inner fender well so I think even at the top of wheel travel I'd clear the fender lip with a hypothetical 15mm increase in width towards the outside of the wheel well. (going from 285 to 315 would = 15mm of sidewall towards the outside of the wheel/fender well)

305/30 or 305/25? On stock 19" rims they fit no problem? I am going to need rear tires soon and would love to go 305.

What is the width of your rims?

There are several sites like this where you can see the effect of changing tire size. In this example I used my AMG Multi-spoke rim specs; 9.5" width and 48 offset. As you can see, virtually no change. Enter your rim specs if different.

https://www.willtheyfit.com/index.ph...9.5&offset2=48

For what it's worth, a lot of people run 20mm spacers on the back of the R231 without any contact issues. That's the equivalent of putting in a 305 without the spacers.

My question, at least, is if the 305 wide tire fits on the stock 9.5" rim. Clearance is not what I personally was looking for as it does fit inside the wheel well. Also, a spacer pushes the wheel out towards the fender lip. When using a wider tire, you have to consider inner clearance from suspension etc.

Another site where you can play around with "Plus" (or minus) sizing your tires. Note: this particular site implies that you should have 10" rims to upsize to 305, while 295 is appropriate for 9.5" rims. Others seem to have upsized successfully on stock rims.

https://www.wheel-size.com/calc/
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Yes, they do "fit" physically. Your question should be, is there a handling impact in doing so and the answer is yes there is a very minor impact for a street car.

Why? What benefit do you think you'll attain by going wider?

I have 285’s on my G with its stock 18x7.5 wheels

Better hookup especially with a tune, and I like the way it looks.

Agreed on the appearance side of things. I've always found the tire setup a little weird. The stock setup has smaller diameter (-6mm) tires on the rear. A 295 section makes the tires the same diameter and the 305's make the rear a little larger (+5mm).

Depends on tire brand/model how much they will buldge.

Ex. continentals you could put 305 vs michelin 295 same width