[Turbo]

The SLK55/R171 comes standard with 225/40-R18, but what's the biggest anyone have used? Without (major) surgery on the car, that is..

Would 21" or even 22" fit? Something like 355/25-R21?? Or 335/30-R24? Dang, yeah now I've started to drool, so I'll stop there

Something tells me that that is WAY to big/wide, but... ?

 

[Avel Du]

I've seen 19" but I think that is far as MB went officially.

You're a builder so you already know the speedo issues etc.

 

[Turbo]

I've seen 19" but I think that is far as MB went officially.

Yeah, that's the biggest you get if you specify the car make and model.

You're a builder so you already know the speedo issues etc.

Indeed. I kind'a assumed that could be changed in the ECU.. ?

 

[Avel Du]

You need @Dave2302 or @Deplore to answer that.

I did change the battery in the key once

 

[jbanks15]

from a site search on similar threads

site:slkworld.com biggest rims wheels on a r171 - Google Search

 

[Turbo]

from a site search on similar threads

Oups, sorry! Thanx for not sending me a https://letmegooglethat.com/ link

 

[jbanks15]

we don't do that
but we use google to search our website

putting this format:

site:slkworld.com biggest rims wheels on a r171

with select keywords

in this instance

gets you this as above post

site:slkworld.com biggest rims wheels on a r171 - Google Search

 

[Turbo]

I do have to agree with some of the sentiments in that post - 20" DO look a bit ridiculous! 19" is just perfect though..

Thanx!

 

[jbanks15]

I do have to agree with some of the sentiments in that post - 20" DO look a bit ridiculous! 19" is just perfect though..

Thanx!

Why stop at 20?

 

[Turbo]

Why stop at 20?

ROTFL!! Yeah, I saw some of those!! 😂😂

 

[Squishband]

Right now, I'm going to demonstrate just how unknowledgeable I am. I assumed that the circumference of the tire would be identical irrespective of what sized rim you put it on. So that 16, 17,18 and 19 inch refer to the size of the rims. The tires themselves are smaller, if you like, in order to ensure that the overall circumference remains the same.

Is that me just being a complete div?

 

[Turbo]

I assumed that the circumference of the tire would be identical irrespective of what sized rim you put it on.

No. It depends on width and profile. The profile is a result of rim diameter and tire width. Somehow.

For example, I did the math a few hours ago:

Roll diameter:
• 225/40R18: 25.1"
• 305/30R19: 26.2"
• 325/30R19: 26.7"
• 335/30R20: 27.9"
• 355/25R21: 28.0"

As you can see, there's a small, but noticeable, difference between the 305 and 325 width tires. EVEN THOUGH it's the exact same rim diam and profile!

 

[Avel Du]

My understanding is that if total diameter of rims plus tyres is constant then it should be ok.

But I am no expert on the matter. That said, I do know other threads have issued warnings about being careful on the subject.

 

[Squishband]

No. It depends on width and profile. The profile is a result of rim diameter and tire width. Somehow.

For example, I did the math a few hours ago:

Roll diameter:
• 225/40R18: 25.1"
• 305/30R19: 26.2"
• 325/30R19: 26.7"
• 335/30R20: 27.9"
• 355/25R21: 28.0"

As you can see, there's a small, but noticeable, difference between the 305 and 325 width tires. EVEN THOUGH it's the exact same rim diam and profile!

Well now I know

 

[Turbo]

Well now I know

Oh, I should have said: Even though it's a "30 profile" in both those cases, the actual "thickness" (as in, distance between inner and outer diameter of the tire in inches/cm) will be different! So the 335 will look thicker (which it also is) than the 305.

 

[b82012]

I run 19s and that should be about the MAX rim size you want on any SLK. As for tire sizes, you can fit up to 245/35 in front and 275/30 in the rear without major fender roll. Of course these will depend on the offset of the 19” rim you choose. For R172s, you want rim offsets no lower than +32mm front or rear... I suppose not too far off for R171s as well.

so to recap: Max rim/tire combo:

19” rims
245/35 front
275/30 rear
+32mm or higher offsets front or rear.

 

[Turbo]

you can fit up to 245/35 in front and 275/30 in the rear without major fender roll.

Perfect, exactly what I was looking for! Thanx!!

 

[b82012]

My rim/tire specs as a guide (check out the stance in my signature pic below)

Front = 235/35/19, +35mm on 19x8.5 rims
Rear = 265/30/19, +35mm on 19x9.5 rims

Good luck.

 

[jet_fl]

I run 19s and that should be about the MAX rim size you want on any SLK. As for tire sizes, you can fit up to 245/35 in front and 275/30 in the rear without major fender roll. Of course these will depend on the offset of the 19” rim you choose. For R172s, you want rim offsets no lower than +32mm front or rear... I suppose not too far off for R171s as well.

so to recap: Max rim/tire combo:

19” rims
245/35 front
275/30 rear
+32mm or higher offsets front or rear.

Not on a 171, 235 is max in the front and 265 in the rear with no fender rolling or rubbing. Your R172 is a bit wider. B82012's listed above are good.

 

[dltslk]

I’ve been running 19s on mine for years and still have the original 18s in reserve. It’s a small car and anything larger would be too much in my opinion...