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Registered 2001 SLK320
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Discussion Starter #1
Hi, I've already made the mistake of dressing my R170 with profile tires that were too low on the front; everything went crazy in the car. I now have the correct sizes on all corners but after replacing the two front tires it is now time to replace the two rears. I really want to go wider but I'm not sure exactly how wide I can go! I'm currently running a 225/55/16 on the rear but factory spec is 225/50/16. This 55 was on the car when I acquired it; only when I went too low of the front is when things went crazy. I want to run a 245/50/16 on the rear, I'm not sure if I should or could go wider but I sure want to. It's only a look I'm after, nothing more. So, any advice, pictures or criticism would be welcomed. I don't think I want to invest in 17" wheels; this car is more of a hobby more than anything else so I'm not going all out with it.
 

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Be careful how wide you go for the rims you have. Wider than the rim maximum will result in premature wear in the centre of the tread as over width tyre will push the centre up.

This is a good guide
It wont format so read carefully

Rim width Minimum tyre width Ideal tyre width Maximum tyre width
5,0 Inches 155 mm 165 or 175 mm 185 mm
5,5 Inches 165 mm 175 or 185 mm 195 mm
6,0 Inches 175 mm 185 or 195 mm 205 mm
6,5 Inches 185 mm 195 or 205 mm 215 mm
7,0 Inches 195 mm 205 or 215 mm 225 mm
7,5 Inches 205 mm 215 or 225 mm 235 mm
8,0 Inches 215 mm 225 or 235 mm 245 mm
8,5 Inches 225 mm 235 or 245 mm 255 mm
9,0 Inches 235 mm 245 or 255 mm 265 mm
9,5 Inches 245 mm 255 or 265 mm 275 mm
10,0 Inches 255 mm 265 or 275 mm 285 mm
10,5 Inches 265 mm 275 or 285 mm 295 mm
11,0 Inches 275 mm 285 or 295 mm 305 mm
11,5 Inches 285 mm 295 or 305 mm 315 mm
12,0 Inches 295 mm 305 or 315 mm 325 mm
12,5 Inches 305 mm 315 or 325 mm 335 mm
 

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Premium Member 2013 SLK250
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The Circumference of the tires needs to be around 78 inches to keep the speedmeter reading the correct speed. To stay at 78 inched with 245's you would need 245x45x16. If the front and back is more than 3% different in Circumference you could also have problems with cruise controll not working.

You did not say with size tire you now have on the front.
 

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If you want to go wider than 245 on the rear you'll almost have to go to a 17" or even 18" wheels. Choices in 245/45-16 are very limited. I assume anything wider in a 16" and the correct diameter would be even more scarce.
 

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Registered 2001 SLK320
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Discussion Starter #6
Sorry, I'm running 205/55/16's up front. Currently there are no problems at all. Do you think the 245/45/16 would bo okay?
 

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245 on 16 inch rims on the front ? NO way. I am only on 225's on 18 inch rims on the front and 255's on the rears
 

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Sorry, I'm running 205/55/16's up front. Currently there are no problems at all. Do you think the 245/45/16 would bo okay?

You should be okay if there is not rubbing on the rear. See below, as the differance is 1%


Front 205x55x16
Circumference1984 mm (78.1'')
Revs per mile811
SpeedometerAssuming that this is OEM tire and speedometer readings are correct >>>

Rear 245x45x16
Circumference1966 mm (77.4'')
Revs per mile818.7
SpeedometerWhen speedometer reads 60mph (96.6km/h) actual speed will be 59.4mph (95.6km/h): 1% slower.

The 245x45x16 are going to be hard to find as this size is a super high perforance tire. Most are track tire.

You might want to look at 225x55x16 on front and 245x50x16 on rear. The circumference are 80.9 and 80.6 with a differance of 0.3 while the speedmeter at 60 would actual be 61.9
 

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Sorry, I'm running 205/55/16's up front. Currently there are no problems at all. Do you think the 245/45/16 would bo okay?
On the rear, yes. As Gbarringer100 said, they are the same diameter/circumference/radius as your fronts. I'm on my 2nd set of 245/45/16's. There are no clearance problems at all.
 

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Nice Articles!

Good article about tire myths, and thanks for the tire size chart. I have a 2001 230 SLK Sport which is a 230 with AMG 32 suspension. It comes with 245x40x17 on the back and 225x45x17 on the front. They work out to be the same diameter, so the car thinks the wheels are the same size. This is a factory option. Those 245's look pretty good tucked up under there!

SP1 SPORT PKG
-inc: AMG body enhancements, 17" x 7.5" front/17" x 8.5" rear AMG 5-spoke monoblock wheels, 225/45ZR17 front/245/40ZR17 rear tires
Invoice: $3846 MSRP $4135
 

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When I can afford it I am dropping my wheels down to 17's. 18 low profiles are not all they are cracked up to be. They make the ride very hard and do not improve handling as the walls do not absorb and shocks and on rough roads make the tread lose contact with the road.

Look at formulae 1 race cars. Very wide tyres but not low profile because the walls need to flex as part of the suspension. Also width doesnt always mean more grip. The wider the tyre the bigger the contact area and this spreads the load making the friction between tyre and road less. Thats why rally cars dont use wide tyres.

Big wheels and low profiles just look good, and as I have said before. By going outside the manufacturers specification on wheels and tyres can invalidate your insurance cover. In the UK it will without doubt.
 

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Registered 2001 SLK320
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Discussion Starter #15
Wow, excellent support! Thank all of you and I see how you may have thought I was talking about 245/45/16’s up front but I absolutely know that would not work; oversight on word phrasing on my part. I’m gonna study the charts some, read a bit more but for the most part I think I want the 245/45 look if I can find them. I recently put the 205/55 up front for the fronts were in terrible need of replacement. MrG, or anyone else; would it be possible that you could send me a few rear shots of your car with this 245/45/16 look on the rear? A picture really helps me visualize better.
 

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If you go as wide as is safe, make sure you buy good wet weather tyres that clear water well. Wider tyres are more prone to aquaplaning than narrow ones.
 

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When I can afford it I am dropping my wheels down to 17's. 18 low profiles are not all they are cracked up to be. They make the ride very hard and do not improve handling as the walls do not absorb and shocks and on rough roads make the tread lose contact with the road.
Great info in this thread. Yeah, it's a trade off. Another thing a smart racing buddy taught me: wheels generally weigh more than tire (and air). Smaller wheels generally mean less unsprung weight.
 

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Pics. Sorry, the shadows don't show it all too well.

Toyo Proxes T1r 245/45/16 rear 225/50/16 front. I don't think these are made any longer, or at least I couldn't find any a month ago. Evidently Cooper bought the tread pattern/mold but they don't come in 245/45/16.





Continental 225/50/16 rear 205/55/16 front.





You should be able to save and zoom in for a better feel.
 

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Per ardua ad cineris.
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Pics. Sorry, the shadows don't show it all too well.

245/45/16 rear 225/50/16 front.

You should be able to save and zoom in for a better feel.
I have AMG wheels with the sports kit
225/45r17 on front
245/45r17 on rear.

Looks good, and definitely zoom for a better feel.
:)

Edit: Image added; shows my rust, and how much we need to worry about sunshine affecting the photographs!
 

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I am now running that same size. I found a decently priced set of 17" CLK wheels in the same style as the 16"s. I'll post a few pics later.
 
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