Hi guys,

I was wondering. my 1990 560SEC has 15" wheels/tires on it.

is there any benefits other than paying more for tires that one could receive from 16" or 17" wheels and tires ?

thanks,
Kevin

Well, other than looking good if enlarged within reason and good taste, they also allow a lower profile tire while maintaining the stock rolling diameter. If you change the diameter too much, you're either wearing out your drivetrain or your braking system, and maybe the suspension, too.

I'm no expert. I learned this from experience, and lately this website:

http://www.1010tires.com/TireSizeCalculator.asp?action=submit

Also over-sized wheels, especially coupled with low profile tires do what is called trammeling. This is where seemingly every crack or aberration on the road causes the tire to wander this way and that.

I put 16s and lower profile tires on my 400 and the car not only suffered no ill effects, but the change slightly reduced the amount of body sway and also eleminates a lot of tire sliding related to hitting the gas and cornering.

__________________
...Tracy

'00 ML320 "Casper"
'92 400E "Stella"

OK, I went from 16" to 18" rims and tires on my SEC. The ride actually improved and the handling greatly improved. I was shocked since I thought it would be the opposite. It felt as if the car were made for 18" rims and tires. The only downside is the potential for bent rims if you have lots of large potholes.

Make sure you get tires with a softer sidewall. The Kumho Ecsta Supra 712's or the Michelin Pilot Sports are very nice riding tires. The Michelin handles better but the Kumho's can tread through water much better, less noise, much cheaper, and ride better. Either one is a good choice.

bigger wheels allow one to use bigger brakes - the main reason why you see them on race cars (except in series that limit wheel size, like F1)

on the other hand, you would also deal with the following:
- if you keep the suspension height stock, your car would look awkward, due to the disproportionate amount of space between the tire and the fender lip
- beyond a certain point, the wheel-tire combination could have more mass (i.e., unsprung mass), adversely affecting ride and handling
- upgrading to larger wheels while preserving the rolling diameter of tires (i.e., plus-sizing) necessarily reduces the tire sidewall height. This degrades the ride quality and transmits more impact loads to the wheels (i.e., avoid potholes)

As most have already posted, there are real engineering reasons for maintaining a stock profile/ratio with respect to wheels/tires. Also consider that MB vehicles still haul ass on the autobahn and handle the mountain curves with ease using the stock setup.

But like any company that mass-produces a vehicle, there are tradeoffs made to satisfy as many of the target market as possible. MB brakes are well designed and can certainly withstand the extra rolling mass of larger wheels, while a well-maintained suspension can also accomodate the more aggressive profile. But Jackie Gleason would have preferred a different kind of ride than Jackie Stewart, so the engineers use the optimum combination to suit both.

I changed my wheels/tires on my W124 to suit my taste in appearance, as I use it mainly as a go-to-work, grocery getter. If I were interested in improving handling and performance, I would have gone to lightweight alloys, not the chrome blocks it sits on today!

I would add that standard roadway curbs allow 15" rims to clear without damage should you scrape against one with your tire. 16" and up WILL encounter rim rash under the same scenario!!!

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

This is not the case with the SEC. The 18's actully fill the tire wells where the smaller rims and tires look akward. Here is a Pic of mine with the 18" rims and tires"

Yes! That is, without a doubt, the softest underbelly of the change. A detail that sends shivers down the spine and provides irritation ever after.

__________________
...Tracy

'00 ML320 "Casper"
'92 400E "Stella"

I agree. I have an older 85 and it came with some 16" ronals, which I sold and replaced with some stock 15" untill I get to the time to restore the car completely. It looks much better with the 16", the 15's are simply wayyyyyyy too small.

Although I do notice you have more wheel well showing on the front tires, I never liked that look, if anything I like to see the front end pointing down a little, and I plan on some slightly larger tires/wheels for my rear.

That is one fine looking automobile.

I also like the 98 CL600 style if a fairing is added, but the sec is one of the all time classics, always caught my eye. Im not too big on most factory styles of rims though.

I did not notice any ill effects on braking. I'm pretty sure that the larger contact patch of the tires will actually surpass the weight difference of the rims and tires and allow for greater stopping ability. However, when jumping to very heavy rims and tires it would have a negative effect but these are not that heavy. This will take care of the weight difference on acceleration:

Low profile tires should improve handling, since there is less sidewall to flex during turns. One major tradeoff is that the useful lifespan of your new, more expensive tires will be considerably shorter than before.

I noticed in another thread that you were inquiring about speed ratings, so you are aware of that aspect.
I have a 6.9 and it has become harder and harder to find a tire in 14" that has an adequate speed rating, but for me, more important, an adequate weight/load rating.
There's just not that much market for tire makers to supply a 14" tire with a 96 or higher load rating and a high speed rating.

I suspect that 15's are headed that way, too, although you certainly have many more choices.

I had some cheap tires on my car as a stopgap and didn't push them at all and they all ended up with belt separations from heat generated by all the weight of the car.

That depends on the treadwear rating of the tire. A 300 treadwear 16" tire will wear just as fast as a 300 treadwear tire on an 18" rims.

I'll take your word. I only know that shorter sidewalls mean more heat, and more heat means more wear.

Most tuners from the 1980's such as AMG, Brabus, Lorinser(to name a few) had rims that were 16-17" in diameter. They, too have engineers who were more performance orriented.