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 600 Tires
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Aggie

26 Posts

Posted - 04/06/2006 :  08:26:12  Show Profile
In my opinion the problems with inaccurate speedometer readings are often overstated and nothing to be really concerned about.

The speed is with these old-fashioned mechanic devices always a kind of educated guess, influenced by a lot of factors. Please have in mind that all speedometers suggest a higher speed than the acutal speed is. A speedometer may never show a lower speed than the actual speed is in reality.

For automobiles until modelyear 1994 the rule is - at least in Germany - a tolerance of + 7 %, for later models + 4 % of the scale is acceptable. This means for the 600 with a scale up to 240 km/h that the tolerance is + 16,8 km/h or in other terms: if we assume a real speed of 100 km/h, the speedometer may indicate up to 116,8 km/h without being considered outside the tolerance.

In theory the speedometer reading with 235/70 R15 tires in comparision with 235/75 R15 tires is approx. 3.3 % higher. For details check out http://www.7-forum.com/service/reifenrechner.php ,the one and only site I know, which takes into account the dynamic effects of the weight lasting on the tires. This effect is responsible for approx. 3 %! Unfortunately the site is in German only.

So DaimlerChrysler does not require a recalibration of the speedometer when using 235/70 R15 tires, DaimerChrysler seems to assume, that the tolerance requirement is still met.

If we do the math, it is clear for me why DaimlerChrysler does not require or recommend a recalibration. Your 235/75 R15 is approx. 1 % smaller than the 225 HR 15, the 235/70 R15 a little more than 4 %. So this is nothing to worry about.

For me much more important is the issue of the availability of reliable tires on an acceptable price level. 235/70 R15 is a pretty common size in our days which is available from all premium brands with a moderate price tag. With 235/75 R15 things look a little bit different at least in Europe. Choises are very limited. All M-100 cars are really heavy, fast and expensive. So they deserve premium tires as well. That is the reason I would never consider an actual Fulda tire for a 6.3 oder 6.9 as discussed in another thread in this forum. Fulda tires of the 60' and Fulda tires for passenger cars today cannot be compared. But this is another story.




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Chris Johnson

USA
3751 Posts

Posted - 04/06/2006 :  11:31:54  Show Profile
I completely agree that the first consideration has to be that the tire is safe for the application. But a lot of us nut cases (and I am at the front of the line) are fascinated by, and strive to achieve, the high standards the 600 set from the beginning.

I think it is true that even Mercedes tolerated a fair amount of error in their speedometers, except in the 600. Five percent errors were not uncommon, and road tests by a variety of automotive publications provided the true and the indicated speed at a broad range of speeds as part of their reviews of any given car. Road & Track was the premier of the publications in the U.S.

The 600 was the odd car out in this aspect. As tested, the indicated speed matched the true speed at all measurement points. The measurement points were 30, 40, 60, 80 and 100 MPH. The error was 0%. Simply amazing. Obviously as the tires wore down some error would have to be introduced, but the the fact that the speedometer indicated correctly at any point in the life of the tires was significant. It is also my opinion that allowing the speedometer to read high by X% was targeted at the fact that the speedometer would progressively read faster and faster as the tires wore. Starting with a speedometer that was some percentage fast with new tires would not be a good thing.

Whether it was just luck (not a principle relied upon by Mercedes) or by design, the 600 achieved a goal not readily obtained. If it was important to them, it is important to me, even if, in the grand scheme, it really isn't important at all. We must use the best tires we can get, but if there is one that better matches the original size, that's the one I want. It's a personal thing.

Chris Johnson
www.300SE.org


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Gerrett

USA
919 Posts

Posted - 04/21/2010 :  20:32:28  Show Profile  Visit Gerrett's Homepage
Has anyone purchased either of the following tires for a 600?
  • American Classic P235/75R15 w/1.6" whitewall
  • Kumho Solus KR21 235/75R15 XL
I'm kind of leaning toward the American Classic because of the whitewall size... and it is rated virtually the same as an XL Load tire.

Gerrett Conover,
M-100 Membership Sec'y
-----------------------
1971 600 SWB
1979 450SEL 6.9
1981 250 LWB
1995 Impala SS
1996 S500
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mtrei

USA
3740 Posts

Posted - 04/21/2010 :  21:28:17  Show Profile  Visit mtrei's Homepage
I once read somewhere about how the actual circumference of a given tire size can vary quite a lot between different brands and models. This is especially important with 4 wheel drive vehicles, where having all four tires the exact same size can be critical for avoiding differential wear. The mounted circumference also changes somewhat depending on the width of the rim it's on. Obviously, tire pressure is important too.

Edited by - mtrei on 04/21/2010 21:29:30
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Art Love

Australia
6258 Posts

Posted - 04/22/2010 :  05:00:06  Show Profile
Gerrett,
I have just replaced a set of Kuhmos on the 600., but I don't know if they were the ones you quote and I don't know if Olaf has thrown them out for me to go and check. I can ask if it is important. Looking through some of the photos, the size is the same but they have Power Pr--- in large letters, so perhaps they are different.
Art
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Gerrett

USA
919 Posts

Posted - 03/10/2011 :  19:38:02  Show Profile  Visit Gerrett's Homepage
quote:
Originally posted by Gerrett

Has anyone purchased either of the following tires for a 600?
  • American Classic P235/75R15 w/1.6" whitewall
  • Kumho Solus KR21 235/75R15 XL
I'm kind of leaning toward the American Classic because of the whitewall size... and it is rated virtually the same as an XL Load tire.


I wanted to bump this post from last year.. I said I was going to replace my 600 tires, but I never did, especially since I took my 6.9 to last year's Meet. But the 600 will make its appearance for the first time in a few years at the Florida Meet, so I want to replace the tires. Soooooo.... any opinions on the above??




Gerrett Conover,
M-100 Membership Sec'y
-----------------------
1971 600 SWB
1979 450SEL 6.9
1981 250 LWB
1995 Impala SS
2000 S500
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cakalues

USA
782 Posts

Posted - 03/18/2011 :  17:34:12  Show Profile
Kumhos are great and very affordable. No problems at all with them. Pretty nice as far as road noise. Had them on two SWB's and a LWB I drove.

Luis
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Gerrett

USA
919 Posts

Posted - 03/19/2011 :  10:48:29  Show Profile  Visit Gerrett's Homepage
Luis:

Overall, I find nothing bad about Kumhos.. I'm on probably my 6th set between all my cars. The 6.9 has Kumho Ecsta summer tires on it. The only negative about them is they get flat spots immediately upon parking that require about 20 miles to smooth out.

As for the 600 tires, I'd buy the Kumhos in a second if the whitewall was wider.

Gerrett Conover,
M-100 Membership Sec'y
-----------------------
1971 600 SWB
1979 450SEL 6.9
1981 250 LWB
1995 Impala SS
2000 S500
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hughc

Canada
70 Posts

Posted - 06/28/2011 :  17:50:16  Show Profile  Visit hughc's Homepage
Gerrett:

What tires did you end up installing on your 600 SWB ? I am over the 10 year mark so time is getting short for my 600 before they need replacing !!
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