Quadrobenz

Nick, I really appreciate all the experimenting you have done along with taking the time to post the results. For info I have no problem with the 285x35 on stock 19x9.5" wheels on the rear. When you have the 265 or 275 tires on the front have you driven them much in the rain? Those widths may hydroplane more easily at speed than a 245.
Tire pressures are also a factor in performance. Having tried many variations I found 42 to 45 front and 36 rear to be optimum for the V12. Steering is much sharper, handling is closer to neutral, rear traction is good and tire wear is even across the tread. Surprisingly the increased front tire pressure makes no difference in ride comfort with the 255x40's. Probably due to the stiff sidewalls.

Welwynnick

I've no idea what to expect with tyre pressures. I usually try to run camber, toe-in and tire pressures that allow the tires to wear evenly across the width. With the 245/45's at the front I used to find myself running high pressures, maybe mid 30's, but never over 40. Isn't that TOO high? At the rear, I found I could run surprisingly low pressures without loosing grip or increasing wear, so I'm often down at 25!

With 275/35 all round, I'd expect to use low pressures at the rear again, but I've no idea what to expect at the front. Maybe wider tires need less pressure, or maybe low profile needs higher pressure? I'm going to experiment.

My journey to work includes some demanding country lanes, and the asymmetric configuration worked really well today (though NOT because it's asymmetric!), just as long as I avoided the pot holes. There's a couple of tightening downhill right-handers where the front end used to push wide before, but now it pulls in very nicely. My car used to be a bit of a one-trick-pony (fast) but now it seems to have learned a new trick.

Nick

Edit: Just thinking out loud for a moment, I wonder if I've gone too far? Even the biggest and fastest contemporary front-engined cars don't have front wheels this wide. Almost everything tops out at 245 or 255, including the big Mercedes, Porsches, Ferraris and BMW's (all fast and heavy cars). The S63 has 255/45/19, and the S65 255/40/20. The M5/6 has 265/35/20 as an option. The Panamera and Nissan GTR are 255/40/20. The Aventador is 255/35/19, and the Bugatti is 265-something. The Audi S8 is 265/40/20, and only the RS7 and Bentley Continental GT have 275/35/20's. A rim width of 9.5" is also pretty extreme.

Do they all know something I should? Should they work or shouldn't they work? The S600 (and any other W215, W216, W220 or W221 for that matter) is available with ABC, and can keep those huge tires flat on the ground - certainly more than the M5 or E63 can. Unlike the uncompromising sports cars though, the suspension is still relatively soft, so it still allows the wheels and the vehicle to move and down over bumps. So the suspension still does a proper job suspending in the middle of a tight corner, maintaining contact pressure and geometry. I think that's partly why it flows round corners, rather than leaping from bump to bump. The more I drive it, the more I like it.

Welwynnick

Oh boy, what have I done now - just bought a set of ML wheels: 19x9.5 all round.
What tyres to fit - 265? 275?
What profile - 30? 35?
Have I gone too far this time?

tusabes

265 40 19 front and 285 30 19 rear?

Welwynnick

Oops, what was I thinking of? I meant to say 20 x 9.5".
I'm thinking about getting 265/35 or 275/30 tires all round.
I don't see any advantage in having the tires staggered.

Nick

tusabes

If you're going to run the same size tire all around I would do 255 35 20

Welwynnick

Finally collected those wheels last night. Damn they're big and heavy. They weigh 32kg each, vs 25kg for the 19's. I've been trying to work out the actual offset; its not stamped on the inside of the wheels for some reasons. The seller thought they were 45mm, but I think they're closer to 40mm. They look nice though.

I've been driving around with 275/35/19's at the front for some time now, and I've gotten quite used to them. There are times when they're quieter than the Michelin pilots sport 245's I used before, but the 275's ARE sensitive to coarse and broken surfaces. On a couple of recent long trips they were quite civilised, so I think the refinement side of things is quite tolerable, and a fair exchange for the handling, which is wonderful. I'm even getting occasional glimpses of real steering feel, and I think there's some useful tuning to be had there.

My reason for posting though, is an idea about staggered wheels. My first thought was that MB decided they were necessary to put lots of power down through just the rear wheels - too much high speed cornering force coupled with accelerating force might be too much for a small contact area, I thought.

But no, that's not a reason. If contact area is a limiting condition, then the worst case will be braking mid-corner at high speed - which will over-load the outside front tire more than mid-corner acceleration will over-load the outside rear tire. Yes, the rear tires have to bear 100% of the accelerating force, but the maximum braking force on the front tires will still be greater, and full braking force can be applied at high speed; not just in the lower gears.

So its the front tyres that actually have the harder time. This has been ratttling around in my head, unresolved, for some time. WHY does everyone fit larger rear wheels? I think I've bottomed this out now, and I'm pretty confident the answer is style and marketing.

If you're just interested in driving, fit the same size front and rear. If you have 245's at the front - fit 245's at the rear. If you want 275's at the rear - fit 275's at the front as well (if you have ABC). As for these 9.5x20's, I think 255's are too narrow for the rims, and the S600 really needs more rubber. It's boiling down to either 265/35 or 275/30, depending on what fits.

Nick

Quadrobenz

I believe MB and others offer staggered figments because people think they look good and it is what many buyers expect. MB had a square fitment on non sport package S class cars in some years. The front suspension was likely optimized for the contact patch of the 245 section tire. Putting the 275 on results in a wider but "shallower" contact patch. In theory the caster setting would change slightly to maintain optimum steering response and tracking. My experience years ago in changing to much wider than stock tires on muscle cars was after a complete realignment of the front end to revised settings the car handled much better. Used a square tire/wheel configuration. Stock was 215, it was changed to 275. Unfortunately the car was undriveable at highway speeds in the rain bcause with the water accumulation on the road it would constantly hydroplane. Ended up going back to 235 section width so I could use the car to and from work on the freeway.

Welwynnick

Quick update.

Judging by the space taken up by the 275-35-19's, I presumed that my ideal size 275-35-20 would be too big. Therefore I went looking for some 265-35 (preferred) or 275-30 (fall back) tires. I guessed the 275's would fit, but the 265's would probably be too big.

Well, I fitted a Pirelli 265-35-20 to the front today, and to my surprise, it fitted fine. Looking at the space available, I'm now turning back towards fitting 275-35's after all. I think it depends on what make and model of tire you use. Not all tires of the same size are actually the same size, rather like clothes.

The 265-35 definitely looked too narrow for those 9.5" rims. I'm going to try it at the back, then go back to the tire shop and ask for a 275-35 to try instead.

Incidentally, my W220 wheel bolts didn't fit properly - they were 10mm too long, so I'll have to get some shorter ones. Didn't see that coming.

Nick

tusabes

A 275 35 20 front tire would be wider than anyone had ever fitted . I'd be surprised if you don't encounter rubbing when turning and fully loaded on dips in the road . Post some pics when you mount them up!!

I recommend the 255 35 20 mainly as its one of the most common and most afordable sizes

I once found a great deal on maybach rims and tires and considered running them but was afraid the tires were too big

Welwynnick

Yes it would, and I would also have been sceptical if I hadn’t tried it for myself.

I don’t see 4 x 275-35-20 as the ideal size, but I couldn’t find four 9.0” or 9.5” wheels in 18 or 19. AMG ML wheels seem to be the solution. I’ve been running round on 275-35-19 at the front for a month with no problems whatsoever.

My daily driver has an ABS fault, so I have to commute in myS600 instead of affording it kid gloves. It seems to thrive on being driven, rather than having its wheels in the air. Apart from needing to avoid kerbs and potholes, there are no great downsides – just the benefits in steering/handling/road-holding/agility.

I think 275-35-20, if they do work, will be pushing the boundaries, and I wouldn’t actually recommend them to anyone. I would strongly recommend 264/40/18 or 275/35/19 all round, though.

Nick

Quadrobenz

For comparison, I have 255x40-19 on 8.5" wheels on my S65. They work fine under normal and performance driving. They will rub slightly when parking with the wheel at full lock and then hitting the brakes. I do not have the tire diameter handy but for comparison the rev's per mile is 769. The 275x35-19 is 781 rev's per mile so it is about 2% smaller in circumference.
A 275x35-20 has 753 rev's per mile so it is slightly larger in diameter as well as wider than the 255x40's I am using. They would not work on my S65 with the stock wheels. It would be interesting to see if they will fit with a different wheel.
For info, the numbers I quoted are for a Continental Extreme Contact DW. Other tires may differ but the relative values between sizes should be the same.

Quadrobenz

I just realized I neglected to re read my comment. Of course a 20" tire will not work on a stock 19" wheel!!! What I should have said was a wheel using the stock 8.5" width and a 44mm offset.

Welwynnick

I also tried fitting the 265/35 to the rear, and though it looked a bit peculiar, I couldn't see any clearance problems. It had about 10mm all round.

I went back to my friendly local tyre shop yesterday, and they changed the Pirelli 265/35 for a Dunlop 275/35. They only charged me the cost of the change, so I'm going back there again. This had a much wider tread - 260mm vs 240mm, and it looked like the tire fitted the wheel properly. The sidewalls were straight rather than stretched. I figured the Pirelli gave me 10mm to play with on either side, so the Dunlop would probably use all of that up.

I fitted it front and rear, and I figured right. I was able to fit the wheel, but it just touched the front suspension upright. The wheel still turned by hand, so its just too big. When you get down the details, the type of tyre seems to be as important as the size. Now I want to try either a Pirelli in 275/35 or a Dunlop in 265/35. I expect they would be about the same size, and both would fit.

There's a compromise to be had with 20" wheels. To keep the overall diameter reasonable, the max tire size should be 245/35 or 275/30 (front or rear - it really doesn't make much difference!). That means the sidewall becomes very shallow, so the ride is harsh and noisy, and the wheel is perilously vulnerable to kerb and pothole damage. 35's are as much of a compromise as I'd want to take.

That's with a standard 44-46mm offset. I think my wheels have a 40mm offset, which pushes them out slightly, up to the edge of the wheelarch. Because of the sloping angle of the front suspension upright, that allows me to slightly increase the wheel diameter and hence sidewall height. I'm trading diameter for width. Hence I can get 265/35's to fit. If you want to use 20's, you can get 275's to fit, but only if you have a stock offset, and accept a crazy low 30 profile sidewall.

When the 275/35/20 rubs the upright, it does so some way up the diagonal, leaving the inside wall of the tire well cleaer of the vertical part of the upright. That means the kingpin offset isn't as low as it could be. I think part of the explanation for the W220's ability to run large wheels and tires (apart from the excessive steering friction) is the relatively uncompromised front suspension.

Like its predecessor, it has fairly low castor, camber, toe-in, roll center, and kingpin offset and inclination. And I don't want to mess that up with heavy wheels, the wrong offset, or the wrong ride height. Or staggered wheels.

So the choice for me is probably to accept narrower 20 inch wheels and tires, or better - stick to 19's.

I think that's my conclusion.

Nick

Welwynnick

Thought I'd add a few pictures of the 265-35-20 Pirelli on the rear, and the 275-35-20 Dunlop on the front. There's a big difference between them. My guess is a 275-35-20 Pirelli would fit fine, but I'm not sure I want to limit myself to one make, even if it's popular. Its the same wheel in the pictures, but I cleaned up the rim in between. Nice wheel; just wish it was 19".

Welwynnick

Dunlop 265-35-20 Sport Maxx GT

tusabes

That looks fantastic , and not far off the 255 /35/20 I would go with, simply due to the wider availability and lower price of that size

Welwynnick

I took it to work, did a couple of school runs, and really stretched its legs today.
The flying machine still flys (Ooops, flies), and the road noise is pleasingly low, but the ride took a slight hit. I'm not sure if its the tire or the wheel, but the 19 rode slightly better.
I didn't push it hard in the bends, but it did feel different. Difficult to describe, it was rather odd, and will take a bit of getting used to. It may be a function of the wear state of the tires.
275-35-19's at the front were a big step forwards, but 265-35-20's aren't so different.
Its a tight fit, but there's no rubbing anywhere.

Nick

Edit: Just checked the 20" tires pressure - the shop had inflated it to 40psi, so Im dropping that down to 30.
Edit2: Moved the 20" to the rear and checked clearance. Just about OK. Drove with no rubbing. Relief.

Welwynnick

About ten years ago, for a short time I had two Jaguars - an XJ6 and an XJ12.
Four years ago I briefly had two W220's - an S500 and an S600 - and fascinating it was too (Airmatic vs ABC, etc)
Now I happen to have two Mercedes again, and this time they're both S600 Biturbos.

Of course they should be the same, but in fact I was probably expecting greater differences. My original silver car now has 161k miles, and I've long wanted something with lower mileage. And Black. The black car has 120k miles, and its smoother and quieter, like you might expect. Although it goes well, the silver car is Eurocharge tuned, and is a lot quicker.

With two similar cars and lots of wheels and tyres to play with, I have the opportunity to make direct comparisons again, and not have to rely on memory so much. What's interesting about the black car, in the context of this thread, is that it has the "wrong" front tyres. For some reason, the previous owner had 265-40-18 tyres fitted at the front, as well as at the rear. The front wheels are 8" vs 9" wide, so it looks a bit odd, but its how it drives that's interesting.

In fact, it drives brilliantly. With its 19 or 20" wheels, the silver car doesn't waft over broken surfaces like a luxobarge should, but the black car certainly does. Its comfortable ALL the time, and feels properly isolated from the outside world. With ABC sport switched off, it initially feels like any big heavy car, but as you apply more lock, it holds its line and digs in (in the dry at least). The amount of grip is unreal considering the comfort. Its a brilliant compromise. I never got to try 275-40-18's all round on the silver car, but I did speculate they would work well. I think they're good enough to say that there's little justification for larger wheels - they're certainly better than staggered 19's.

There's something you don't see every day:



Nick

wallyp

Apparently Nick, for many folks, stylin' is more important than function. Those extra inches in the wheel diameter is the most critical factor...

Welwynnick

I know what you mean. I've said how I think 18's or 19's are ideal, but I now have 20's on the silver car, so I'm quite the hypocrite. The ride is rough, but the road noise is surprisingly low.

Wheel diameter does seem to be the most important thing - I've seen many wheels advertised where only the diameter is given, the width isn't mentioned at all. And of course staggered wheels are seen as an advantage. I found that fitting wider wheels at the front tended to fill out the arches as well as larger wheels - see the pictures in posts #3 and #16. In reality, I think for a car to work well, you need the wheels to be as SMALL and light as posible, consistent with fitting the brakes. They should then be as wide as is necessary to cope with the weight. Putting 265's or 275's on the front, of a V12 in particular, is a great benefit.

Here's another secret - modern low-profile tyres are much quieter than old ones. Manufacturers seem to increase wheel sizes by one inch with every new generation of car, which means fitting more and more agressive tyres. Other things being equal, these will be noisier, but car makers won't accept that, and tyre makers seem to be finding ways to get round that. Tread patterns have converged to having a number of straight longitudinal ridges, and few lateral blocks. Maybe that compromises lateral grip in some respects, but that seems to be way tyres are going, and it does seem to work.

The front of the W220 seems to be most prone to tyre noise, perhaps because all the suspension joints are mounted dirctly to the chassis, there's no rubber mounted subframe, unlike the rear. My car was quite prone to road noise from my old Pirelli 245/45/18's, but I can't say that the 275/30/20's are any worse overall - maybe they're quieter at low speeds and on smooth surfaces, and noisier at high speed or on coarse surfaces.

Nick

wallyp

While everything in life is a trade-off, there are few things with as many trade-offs as automobile tires. Every tire is a balance of dry traction, wet traction, tread life, noise, cost, appearance, etc., etc.

I live in the Atlanta, Georgia area. We get more rainfall per year than does Seattle. I can count the number of time that I have slid a car on dry pavement on my fingers and toes - wet pavement is a different story. That makes wet traction one of my higher priorities.

It is very obvious that quite a few of our fellow Forum members place "stylin" much higher on their priority list. Very near the bottom on mine.

Welwynnick

Not as much a compromise as I thought.

Last week I reached my end-game, and finally fitted 275/30's on 9.5 x 20 rims all round. This was beyond my ideal configuration - I didn't want to go below 35 profile at all, and I quite feared the worst with all four wheels on 275/30's, fully expecting to want to go back to 18 or 19's.

However, I've had the opportunity to put a lot of miles on those wheels. My son broke his foot camping, and I had to go rescue him on Friday. So - which car to take - Ford or Mercedes? Mercedes of course! It was a long round trip, almost 8 hours of driving - just the sort of thing to magnify any little annoyances. I've also been driving to work in it this week.

The verdict? Well, I have to avoid kerbs and potholes like the plague, and small bumps are certainly less rounded and cushioned, but overal its still quiet and comfortable. Quite acceptable for even a long journey (which is really its raison d'etre). I said above that I thought the big Dunlops and Pirellis were quiet on smooth surfaces, but noisy on coarse ones. Well, I have to say that OVERALL its probably quieter on the 20's than it was on the 18 or 19's, which is some surprise. That means the type of tire is more important than the size.

The tires I'm using are quite specific - Dunlop Sport Maxx GT at the front, and Pirelli P Zero (not Rosso) at the front, and I can say that they're quiet. Perhaps they compromise grip for refinement, but I'm happy with the compromise. Now when I drive the car, I think how quiet it is every time, its far quieter in every respect than when I got it, and the tyres are just another improvement. And the handling is fantastic of course.

Of course, using new tires in the stock size would be quieter still, but I found the overall ride/handling compromise has got BETTER in this form, and there's no going back for me.

Which means eating humble pie, because I've been ranting for years about how over-size wheel and tires ruin a car.

Nick

Welwynnick

I finally plucked up the courage to get a set of AMG ML63 wheels, and try to fit them:



The spec is 20x10 5x112 ET46. Much to my relief, they fit perfectly:



Its a tight fit, but its spot on, and doesn't need spacers, or risk rubbing anywhere. Very happy indeed.



Nick

tusabes

Daylight pics please !! Looks great