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This past fall, with 185/70r14 tires on the front and back of my 1985 300d, I clocked the 0-60 time in a fairly flat stretch of road near my house at approximately 13 seconds, which I understand to be about average. Since then, I have installed 205/70r14 snow tires on the BACK of my car (but left the 185/70r14's on the front) and have been driving all winter that way. Since my oil change, I decided on a whim to clock my car for 0-60 on the same stretch of road, and found to my dismay that the car's 0-55 time was over 18 seconds (I couldn't get to 60 before I got to an uphill stretch and had to call off the test). Several other spontaneous tests in the area yielded the same results.<br> <br> What I wonder is if putting bigger tires on the back of the car gives the engine less leverage with its torque, and therefore a slower 0-60 time or if there's something I overlooked when I changed the oil?<br> <br> I understand that the speedometer runs off of the front wheels, so changing the back tires won't affect my trials.<br> <br> I have to buy a new set of 4 all-season tires in a week or two anyway, and I wonder if a certain size or brand is recommended to give me optimal acceleration time.<br> <br> -Jerrold<br> 1985 300d<br> 229,900 miles
 

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Changing the rolling road radius for a whell tyre combination his will change your acceleration in the same way it would effect your speedo readings if you did it on the front wheels.<br> <br> 185/70 means 185 millimeters with 70% of that as the measurement of the sidewall.<br> <br> Going to 205/70's means the sidewall radius is increased from 70% or 185 mm to 70% of 205mm.<br> <br> Bigger rolling radius means higher gearing. Higher gearing means higher top speed (in theory) and slower acceleration.<br> <br> If you want the bigger footprint of 205 but same gearing you would need 205/65 or 205/60's.<br> <br> Andy
 

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Another question: my 300d currently has the early 80's 5-bolt 14' aluminum alloy wheels. The stock tires that come on those wheels are size 195/70-14. What is the widest wheel size that I can get onto those wheels? Can I put 205's on those wheels, or would I have to buy wider wheels? I have 205/70-14's on the back right now (snow tires) but they're on old steel wheels from a pickup truck. I'm buying a new set of all-weather tires, and I wonder what the widest tire is that I can get away with.<br> <br> -Jerrold<br>
 

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I've said this a lot in other posts, and I'll repeat it again. Use the stock tire size on stock wheels. Period. If you want bigger tires, get a wider wheel to mount them on. A bigger (wider, etc) tire is NOT better. It will 'swim' on the narrow wheel and reduce handling feel. I recommend getting the best quality 195/70/14 tire you can for the stock wheels, if you don't want to spend $$$ for different wheels. I got Yokohama Avid H4's for my '84 and they are really nice, while the cost is reasonable.<br> <br> Note: You can get 124, 202, 203, 208, and 210 chassis wheels (most all later C- and E-class) with tires pretty cheap. There's a guy in LA who's selling a set of ~2000 E320 wheels & tires for $400. They're 215/55/16 on a 16x7.5 wheel. That would be the best way to go, IF they'll fit. I haven't tried any measuring to see if those wheels will fit a 123 chassis...<br> <br> <br> Good luck,<br> <br> Dave M. :)<br> 1987 300D - 229kmi (17-inch Carat wheels)<br> 1987 300D - 237kmi (1999 C-class Sport wheels)<br> 1984 300D - 207kmi (stock wheels & tire sizes)
 

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I am selling my 300D and have some additional parts if your interested (tires and rims)<br>  <br>  <br> The Car:<br> http://www.shutterfly.com/my/osi.jsp?i=67b0de21b31c0ace252e<br> Parts:<br> http://www.shutterfly.com/my/osi.jsp?i=67b0de21b31d584105c4<br> <br> http://forums.mbnz.org/forums/W123/vthread.asp?messid=674<br>
 
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