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No, I am not getting rid of it. It's a big, heavy car (over 2T with fuel/passengers, close to 2.5T four-up!), and the default wheel/tyre setup isnt the most agile.
245-width front tyres on a vehicle this heavy will naturally understeer, and 275 rear tyres are effectively boat anchors with the power/torque delivery of the biturbo V6. It understeers initially into a corner, and understeers or is at best neutral under power on corner exit (despite the 31:69 F:R torque split).
It also doesn't help that I'll pay close to AUD$500 each per front tyres and AUD$600 (or more) per rear tyre. Finally, the 20" rims (and licorice-strap tyres) and Sydney roads are just not friends.
I am truly amazed that the ride is as good as it is (the air suspension is truly amazing), but I know I am one average Sydney pothole away from a bent/cracked wheel (I have the lovely to look at but made of soap/butter AMG multispoke wheels).
So, I have been considering changing to a squared setup - it answers several of my challenges and provides numerous benefits. To start with, if I go with something bigger than 245 (realistically, 255 is it), it gives more lateral grip at the front end, which will help turn-in. Such a setup gives fractionally less grip at the rear, meaning there will be a little more rear adjustability - the car will rarely (and never on public roads) do the sort of speeds that demand 275 width rears, so I am not concerned about downsides here.
A square setup is nicer on the drivetrain - exactly the same front and rear, so the 4Matic will be happier. Smaller tyres are considerably cheaper. A square setup means I can rotate tyres front to rear and thus make better use of tyres, replacing them together and getting discounts (buy 4, get one free, etc). I also aim to try to use a "common" tyre size, which will keep prices down. Having removed front and rear wheels recently, another benefit is going to be unsprung mass - the stock wheels are really heavy.
The fun part now though is the sizing.
18" are theoretically possible, but very tight over the AMG brakes. Apparently BBS have 18" wheels that fit, but I am not sure that I want to go that small, so it seems 19" wheels are where I will land. Using 255 width tyres, the closest match to factory is 255/35R19 - which also is one of the most common size.
The issue then becomes one of width and offset. And this is where things get interesting.
We'll start with the fronts - the rear is a lot more forgiving. The stock front wheels are 8" wide and ET20, with a 245 width tyre.
Trying to get a 255 width tyre between the suspension and front guards is the fun bit. I believe 255/35R19 on 19x9ET18 will fit on the front (remember I want a square wheel setup, this ET is effective, not absolute).
The tyre width is more concerning than the wheel width (wheels don't deflect under steering forces, tyres do, and the tyre sits wider than the wheel) - 255 tyres are (all things being equal) 10mm wider than 245s, 5mm wider on the inside and the outside. Because the centre of the wheel/tyre combo sits 2mm further out than ET20, this means 255 tyres on an ET18 rim will be 3mm closer to my suspension (there's a good 2cm there on the 245 tyres on stock wheels) and 7mm closer to the guards than 245 tyres on stock wheels.
There's about 15mm of space between the face of the stock wheels and the front guards, so this will sit nicely.
19x9ET18 on the rears (compared to 20x9ET49) would be *stupid*. What does make a lot more sense at the rear is ET30 - it pushes everything 19mm out, but then the tyres are 20mm narrower, so I get about 9mm more poke than stock - given the stock wheels sit ~2cm inside the guards, this will still sit inside the guards, just not as much as stock.
So, how do I get ET18 and ET30 out of a single wheel spec? 12mm hubcentric spacers on the front... So, 255/35R19 tyres on 19x9 ET30 wheels with 12mm spacers on the front axle. I think this is the goldilocks setup. Anyone disagree?
You've obviously thought a lot about this dilemma... I think limiting spacer usage to one end of the car is the right way forward, so your idea of 12mm spacers on the front and none on the rear seems ideal.
Now whether you're able to find some 12mm spacers by a reputable company is another issue. And then you'll probably need longer lug bolts to compensate too. And are you able to find wheels with the specific ET30 offset? Maybe you'll need to get them custom made.
I don't have any specifics for you, especially when it seems like you have a clear assessment of your situation. I do think your thought process is excellent and see no major flaws with your plan.
Personally, I despise spacers, but it's obviously necessary in your pursuit for a fully square setup. Good job!
You've obviously thought a lot about this dilemma... I think limiting spacer usage to one end of the car is the right way forward, so your idea of 12mm spacers on the front and none on the rear seems ideal.
Thought and testing. A mate with a BMW has several wheel and tyre combos available to him, and we tried fitting several as part of this process.
Now whether you're able to find some 12mm spacers by a reputable company is another issue. And then you'll probably need longer lug bolts to compensate too. And are you able to find wheels with the specific ET30 offset? Maybe you'll need to get them custom made.
We tested with a set of 12mm spacers as part of the work with my mate. Totally agree that spacer must be hub-centric, and 12mm is the smallest that come hub-centric.
Wheel bolts is interesting. My stock wheel bolts were actually bottoming out (and in an interesting way) on my mate's Apex wheels - because they are thinner through the wheel than the stock wheels. The interesting way is that the bottom out was that the stock bolts arent threaded all the way along the shaft, and I was running out of thread. I will need to check the thickness of the new wheels (I am having them custom-made) before deciding on the bolt lengths.
I don't have any specifics for you, especially when it seems like you have a clear assessment of your situation. I do think your thought process is excellent and see no major flaws with your plan.
I've theory-crafted for weeks, testing on Saturday largely confirmed and refined what I already suspected.
The fronts are the biggest constraint. I considered ET35 wheels, but 15mm spacers for an effective ET20 puts the 255 width tyre too close to the suspension, and if I cant get that extra width at the front then I don't get the extra front-end bite I am looking for, and on the rear they'd actually sit 1mm further inside the guards (and thus need spacers at the rear as well).
Personally, I despise spacers, but it's obviously necessary in your pursuit for a fully square setup. Good job!
I am with you here, but they are necessary if I want a squared setup (and I do).
Not sure if this helps with your offset, width or tire questions but I am running 20x8.5 ET20 and 20x9.5 ET45 Brabus Wheels with 255/35/20 and 285/30/20 Michelin PS AS4. No rubbing and they ride so much nicer than the stock wheel and tire setup.
Thought and testing. A mate with a BMW has several wheel and tyre combos available to him, and we tried fitting several as part of this process.
We tested with a set of 12mm spacers as part of the work with my mate. Totally agree that spacer must be hub-centric, and 12mm is the smallest that come hub-centric.
Wheel bolts is interesting. My stock wheel bolts were actually bottoming out (and in an interesting way) on my mate's Apex wheels - because they are thinner through the wheel than the stock wheels. The interesting way is that the bottom out was that the stock bolts arent threaded all the way along the shaft, and I was running out of thread. I will need to check the thickness of the new wheels (I am having them custom-made) before deciding on the bolt lengths.
I've theory-crafted for weeks, testing on Saturday largely confirmed and refined what I already suspected.
The fronts are the biggest constraint. I considered ET35 wheels, but 15mm spacers for an effective ET20 puts the 255 width tyre too close to the suspension, and if I cant get that extra width at the front then I don't get the extra front-end bite I am looking for, and on the rear they'd actually sit 1mm further inside the guards (and thus need spacers at the rear as well).
I am with you here, but they are necessary if I want a squared setup (and I do).
Not sure if this helps with your offset, width or tire questions but I am running 20x8.5 ET20 and 20x9.5 ET45 Brabus Wheels with 255/35/20 and 285/30/20 Michelin PS AS4. No rubbing and they ride so much nicer than the stock wheel and tire setup.
8.5" wide ET20 and 255 tyres sounds about right for the front, no doubt, but I'm hoping to avoid the tyre bulge that comes with putting 255 tyres on an 8.5" wheel.
Those rears sound meaty.
I imagine it'd handle better (better turn-in, plenty of rear grip), but how much better does the car ride than stock? There's very little difference in sidewall height between the stock tyres and your wider ones.
Tyre pricing, rotation, different grip characteristics (see my first post - I want more front grip than stock and a little less rear).
Me too.
I just did this on an E63 and ended up with 285/35 front and 295/35 rear.
I do not know how much more or less room the E43 has.
If it is the same wheels as E63, you have a TON of space to work with
Me too.
I just did this on an E63 and ended up with 285/35 front and 295/35 rear.
I do not know how much more or less room the E43 has.
If it is the same wheels as E63, you have a TON of space to work with
0.7% variation from front to rear isn't terrible, and on a 20" rim, that profile on those widths gives a decent sidewall. Nice work!
I wish as much space as an E63!
The E63 got significantly flared guards as well as a different suspension and braking setup.
The rear on the E43 has plenty of room - I am sure I could go for 10" or wider, and 295 tyres (whilst expensive) would fit just fine - pending appropriate offset, of course. But the front is tight - just getting a 255 tyre to fit at all is challenging enough, and really depends on a goldilocks offset, which is why I've settled on ET30 with 12mm spacers for an effective ET18.
8.5" wide ET20 and 255 tyres sounds about right for the front, no doubt, but I'm hoping to avoid the tyre bulge that comes with putting 255 tyres on an 8.5" wheel.
Those rears sound meaty.
I imagine it'd handle better (better turn-in, plenty of rear grip), but how much better does the car ride than stock? There's very little difference in sidewall height between the stock tyres and your wider ones.
I prefer 1 width wider than OEM sizing when it comes to tires. This is the perfect look - it is not too meaty. The car turns and tracks so much better with this tire setup too, and seems to handle the road imperfections better. The factory 245/35 are slightly too firm. I put the stock setup back on this week (nearly new MPAS4 245/35 and 275/30) as I was getting some repairs done and it reminded me how much better the new wheel and tire setup feels. Hope this helps!
Last edited by 6speeddave; Jun 10, 2026 at 09:28 PM.
l I will need to check the thickness of the new wheels (I am having them custom-made) before deciding on the bolt lengths.
I considered ET35 wheels, but 15mm spacers for an effective ET20 puts the 255 width tyre too close to the suspension, and if I cant get that extra width at the front then I don't get the extra front-end bite I am looking for, and on the rear they'd actually sit 1mm further inside the guards (and thus need spacers at the rear as well).
who will be making your wheels?
And considering that you're going from 245 /275 to 255 square, I think you'll have plenty of front end bite.
I prefer 1 width wider than OEM sizing when it comes to tires. This is the perfect look - it is not too meaty. The car turns and tracks so much better with this tire setup too, and seems to handle the road imperfections better. The factory 245/35 are slightly too firm. I put the stock setup back on this week (nearly new MPAS4 245/35 and 275/30) as I was getting some repairs done and it reminded me how much better the new wheel and tire setup feels. Hope this helps!
That sits very nicely, that's the look I am after in terms of where the tyres sit in relation to the guards. The stock setup is very much tucked in...
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