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Is anyone running the normal front size 205 55/16 tire on the rear? Not sure if the rear rims are wider or if the rims are all the same all around. I'm looking to run the same size tires all around and get away from the fat noisy expensive 225's. Appreciate hearing from anyone whose done this.
 

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Don't know whether it was an option, but I believe that the standard was to have 16x6.5" rims on the front, 16x7.5" rims on the back. (On my 01 anyway. The Sport Option was for 17x7.5 f/17x8.5 r.) Typically this is referred to as a staggered setup. I would generally argue that there is really very little physical benefit to this, and it does makes it more difficult to get the proper sized (diameter) tires.

This is important since the stability system works by comparing rotational speeds of the wheels at each corner, and different diameter tires (f/r) normally give slightly different speeds to begin with. Stock 16s are within about .08%, Sport 17s are about 1%; the same size wheel and tire at each corner should equal 0% difference. With a car as equally balanced as the SLK, it's hard to imaging that we can gain much benefit due to the small differential in tire widths with a staggered setup, particularly under normal driving . . . But the cars' suspension was tuned for this differential, so the different setups might feel a bit different. Typically wider tires will feel stiffer anyway, but there are other factors involved in that too.

So mostly it's aesthetics with perhaps some ride quality issues. Of course you can't "rotate" the wheels if they are from a staggered configuration; so overall life might go down a little, but I've never had an alignment/wear issues on my tires. If you have staggered rims, the tire OD will be slightly different even if you have the same sized tire mounted on each. (This is more probably/doable with a 16" rim than a 17" rim.) This might make the handling a bit iffy too if you were ever to rotate that set.

So what you ask is very doable, particularly in you have a set of non-staggered rims already available . . . But frankly for cost, with the selection of tire prices available, I think I would just drop to the next less costly brand and keep the proper sizing. (Noise is more a function of the tread pattern and depth, and that is very hard to judge depending on the types of pavements you typically drive on.) Generally, I don't scrimp on the tires (though I don't buy the most expensive either) since that is where all the action really happens . . . for good or bad . . . .

Hope that helps.
 

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plus one to that

I learned very quickly never to skimp on tyres or brakes...or any other safety feature. If you shop around, you can probably find a different tyre brand for less cash that performs as well, or maybe better.
I have been doing that for years, and have gone from the Michelin Pilot Sports that came on my first MB via Avon, Barum, Falken, Kumho, Toyo, Pirelli. None of them failed to deliver, none of them left me feeling 'awkward', and they all cost considerably less than the really Big name brand 'recommended' choice.


It might not assist you in the US, but if you look at the mytyres website, or black circles, which we can easily take advantage of in the UK, they have user reviews as well. You must have something similar in the US. I can't believe you'd lag behind Europe when it comes to selling tyres.
 

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See if your owners manual has alternate wheel and tire combinations listed. On our 2015 SLK, the car came with 18" wheels, wide at the back, typical SLK. The manual has a "winter" tire setup listed with all the wheels and tires being the same size and diameter, 225/45/17 in our case. I wanted snow tires so I bought a set of wheels and tires in this "winter" size. I used Tirerack.com and they offer the whole package. They shipped four tires mounted to the wheels, fully balanced, with the correct lug bolts, to my house. All I had to do was bolt them on, and the car is pretty good in the snow. The new combination has the same diameter as the original tire/wheel. I think the handling is slightly different/worse but don't exactly know whether it's just the totally different tread compound. I would be able to swap these tire/wheels from front to back, not possible with the originals. Left to right rotation depends on the tread pattern - some tires won't allow it.


I think if you have staggered widths now, the front wheels are different widths and offset than the backs. So you need at least two more front wheels to get all tires the same size and some rotation ability.
 

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Is anyone running the normal front size 205 55/16 tire on the rear? Not sure if the rear rims are wider or if the rims are all the same all around. I'm looking to run the same size tires all around and get away from the fat noisy expensive 225's. Appreciate hearing from anyone whose done this.
I ran my old SLK 230 with 205/55/16 all round with no problems. You will need the same size wheel as the fronts.

Mark
 

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Discussion Starter #7
I appreciate the great responses. I acquired a set of front rims. So I'm going to mount Pirelli P7 AS 205 55 16' and run them on the rear with my same size Michellin fronts and see how the four perform together. The Pirelli's are the quietest tires I've run and the price is very good for a 70k Tire. If for some reason I'm not satisfied I'll put the Pirelli's on the front and put the 225' pirelli's on the rear. Thanks again for the inputs
 

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From the manual it says the abs/esp system works best when on winter tyres.

Winter tyres are only 205/55/R16's all round.

Summer tyres 205 all round is standard.

Rears optionally have wider wheels and tyres.

I'm currently looking at getting new rears on my 230k trouble is rears are all high performance types and fronts are mostly economy types.

To get matching front and rears I seem to be limited to
Goodyear - Efficient grip performance
Yoko - V105S
Pirelli - P7 Cint's
 

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From the manual it says the abs/esp system works best when on winter tyres. . . .
This is basically because of the diameters. The closer the diameters are, front to back, side to side, the better the ABS/ESP system works. (At least in the sense of knowing what is going on. If the ABS/ESP could be reset/calibrated for the set of tires/wheels on the car, it would make little or no difference.)

You can easily calculate the "ideal" tire diameter from the information on the tire sidewall. (This of course assumes the tire is inflated properly, on the correct rim, etc.)

So, 205/55R16's = 205mm section (tire) width, with a 55% tire height . . . (As compared to the section width.)
Ideal tire diameter = 16" + (205 x .55 x 2)/25.4 or 24.88 inches

That would be for my fronts, and the staggered rears would be 225/50R16's . . .
ITD = 16" + (225 x .50 x 2)/25.4 or 24.86 inches. (a negligible fraction smaller.)

The only way to get 0 difference is to have the same tire size on the same rim width at all four corners. (Inflated to the same pressures, same wear, etc.)

I would believe that the Manual is considering that the absolute performance on winter tires is of less importance than stability and control. From my research, it's almost impossible to get a staggered set of wheels to match 100%, but considering what the differences are with the OEM tires, something within a percent will typically give minimal problems. The "sport" option on the 170 is just over 1%.

The only time the ABS/ESP kicks in is when it thinks a tire is sliding beyond a certain amount; so the larger the tire delta, the closer to the edge the system already thinks it is. What you don't want is a delta so big that the ABS/ESP sees the different tire rotational speeds and thinks that a tire is sliding all the time, or every time you turn a corner. (In which case you would have to turn it off.)

Although mixing and matching brands isn't considered the best thing to do, keeping the same type/age/wear of tire on the same axle is desirable!! There is also some new thought to keeping the better/newer tires on the rear axle (assuming you have that choice) since most cars are already setup to lock up the fronts before the backs. This is to keep the car from swapping ends under panic braking, (very undesirable) and new tires on the front/old tires on the back tends to defeat that objective. (This is true for dry, wet or snow.)

Some things to think about anyway.
 
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