SL65MONSTA

SL65 2004 model comes out with 19" wheels, I have gone up a size to 20" now am getting ESP and ABS warning codes on dash, called local wheel shop they say wrong size, what can I fit onto it without my car going limp mode. I have noticed many people have various sizes on there cars. How did you get away with it ? without the car not spitting out codes?

Ghostty

That's really weird. What sizes did you have and what do you have now?
Did you mix the rear and front tire sizes?

MB setup fits up to 255/30/20 fronts and 305/25/20 rears. But i bet guys went beyond that

SL65MONSTA

at moment i have 255/30/20 on front which is okay, the rears are 275/40/20 , I've been told the rears can be 305/25/20 , 295/25/20 or 275/30/20 . But I have noticed members on this forum with all types of sizes how do they get away with it ? some people are running radials on the rear! this is what i wanna do to, to get maximum traction.

Ghostty

idk, i guess there's a certain size match up for the fronts and rear when you're changing tires. I just bought last sunday some 20'' and going monday to put them on and see if anything pops up. The sizes that are on the wheels are 245/35/20 fronts and 285/30/20 rears (hoped the rears would been wider )

Btw just made some research on the web - here's the issue
You're running 255/30/20 front. The total tire height it's at 92mm.
Now when you're looking at your rear ones you have 275/40/20 - the total tire height is 106mm
If i'm right then the car recognizes the new levels of your suspension as errors, and throws up the codes. Your rear suspension apparently is 1.4 cm taller.
Usually when changing tires you should try to keep both front and rear at the same ratio as it was previously.
For 255/30/20 front i'd say the sizes you should be looking at is 285/30/20 (99mm) or 305/25/20 (97mm).
check with a good tire shop or make some research on forums, you'll find lots of answers

SL65MONSTA

a lot of places have recommended not up or down 3% larger diameter then what the original outer tyre size is. Found a calculator that does it, but still curious to know how everyone else is running different sizes on the SL without the car not liking it

Ghostty

As long as you increase the fronts by same % as the rears you should be fine. But yours might be different - the fronts got bigger by X % when the rears by Y % , that's what I mean. It should have been same X %

What was your previous setup?

lawrence99

Try this tool : http://www.rimsntires.com/specspro.jsp
















rear tire aspect ratio to too large for a 20" rim on our cars

Ghostty

Idk, JUst mounted today my 20'' and they fit just fine

Actually i was thinking did you have your car scanned? To see what codes exactly you have? Because there might be more than 1 thing that triggers those two lights

Do that for start, maybe you'll get some answers

lawrence99

Comparison of oem tire set to your choice of tires:
With oem standard tire sizes the front wheels are slightly larger. So the rear wheels rotate at 1.008 times the speed of the fronts or 0.8% faster.
With your set up the rears are larger than the fronts. So the rear wheels rotate at 0.909 times the speed of the fronts or 9.1% slower.




Comparison of oem front to your choice of front & oem rear to your choice of rear:
Front tire size is nearly identical with you choice being 0.9961 percent smaller.
Rear tire size is inverse and a greater offset being 1.1038




By doing the math the configuration that you have chosen is 10.77 % off from factory design.


This being said and if it is possible (don't know the brand of tires you have) keep the fronts and get 295/25/20 and remember that all your choices need to be XL to handle the weight of our cars.

lawrence99

look to the charts showing oem tires vs. your choices

SL65MONSTA

so it has to be within 3% up or down apparently the wheel shop said, now running 255/30/20 on front and 285/30/20 on rear Pzero, thanks for all the input guys

Ghostty

Did the lights turn off? If so - pics are due with new rims

And play with tire pressure, for better ride. The guy at the tire shop pumped mines to 38 all around. Driving on hot asphalt kicked it up to 42 - i was driving like on rocks! Awful experience. Lowered to 32 fronts and 36 rears. Much better, but still planing on taking it to 30 / 34 for an even smoother ride FWI - door sticker says 26 fronts and 29 rears - of course with stock wheels

SL65MONSTA

Only problem with lowering your tyre pressure for a smoother ride is your wheels are much more vulnerable to damage, if a pot hole or hump in the road is hit the tyre profile will bend much easier! I know from experience. 34 seems perfect !

SL65MONSTA

lights all off dash now getting fender rubbing on the wider front tyres running 255/30/20 time to lip the fenders maybe

Welwynnick

255/30/20 shouldn't be to big.


What offset are you running?


Nick

SL65MONSTA

im not exactly sure hey ?

Ghostty

Fender rubbing? Have you lowered the car? They should fit without any problems!
But as Welwynnick says lets start with an offset. Mines are 245/30/20 offset +15 fronts. But you should be able to work up to 25 or so.

You know what's up with the offset, right?

SL65MONSTA

yeah I think my wheels offset is the issue ^ they are somewhat concave wheels. Time to lip guards

Ghostty

Mines are 245/35/20. Double checked the size. Took a pic also. Look how much space i have between the tire and fender. So i'll assume you lowered the car, that's why

SL65MONSTA

sorry i think i was not very clear, what i meant was is the guard rubs on the tyre over road humps and steep driveways or crests in the road , it rubs for a second if that

SL65MONSTA

5 Feb 2018

Ghostty

Me like it

P.S.
i see where the tire hit the fender

SL65MONSTA

SL65MONSTA

not sure of a way around this problem other then driving the car with suspension "high"

Ghostty

Did you lower the car? That would be it ironic to lower the car and drive in HIGH setting after 😄
also depends on your tire width, I'd say it should be greater than 9J, is it?

Regards