esses

hi guys

PSS is on backorder from TireRack. What is the next possible size to run on stock everything?

PkB2014

265 and 275 fit stock rim.

esses

many thanks.

am i correct in assuming that 265/35/18 would be the next best size, when keeping the front 235 in terms of diameter?

bhamg

Yes, definitely.

whoover

That tire will be a little over 1% off in terms of rolling radius:
http://www.tacomaworld.com/forum/tir...5r18-265-35r18

Personally, I wouldn't use a tire that's any more than .5% off. Of course, it's your car and a lot of people go with tire fitments that are off this much, but you should know exactly what it means.

The car's axle plane will be off by 3.5 mm from the engineered height from ground (half the difference in the two tires' diameters). So you have to ask yourself how you'd feel about a shop getting your rear alignment wrong by 3.5 mm. Race cars (and even race suspensions for our cars) are much more adjustable both front and back so that alignment can be dialed in with different tire diameters, offsets, etc., but a stock rear end will just be out of alignment, if only slightly. With a suspension as carefully engineered as ours, it's asking for handling differences and accelerated tire wear.

The other issue to think about is ESP/ABS. A 2% difference between expected and actual revolutions per mile tells it the car is skidding. You're using half of that "normally," so you can expect the ESP to cut in sooner than it should. Again, at 1% variance you'll be in the "probably ok" area most of the time, but you shouldn't be surprised if the car notices.

Once again, for a car like this I'd keep it within .5%. The bad news is that there isn't an 18" size that will do that. But as an example, notice how close a circumference match the stock 507 19" tire is to the stock 18":
http://www.tacomaworld.com/forum/tir...5r18-255-30r19

KIS007

Is there a way to increase the tire size on the rear and the front without causing potential problems? Also, thank you in advance for sharing your knowledge.

whoover

Afraid not. Normally the only way to change tire size is to change wheel size too. Front vs. rear revolutions-per-mile disparity is one issue, but frankly it's not the biggest problem. A tire-circumference disparity at either axle means misalignment (front or rear) and out-of-calibration traction control, etc. It's slightly worse for the computers if it thinks that the rear wheels are going farther than the front, but even if they both change the same, they know that the wheels are not spinning at the right speed for the car's speed and get paranoid. The only way to dial back the car's engineering is to have a fully adjustable suspension and be willing to experiment plus be able to recalibrate the electronics. Usually that means being part of a race team.

That's why the normal +1 fitment, say, increases tire width and wheel size and drops profile, with the goal of keeping the circumference the same. For a car that you want to drive like it was engineered to drive, that .5% figure is the standard. Like I said, people want more rubber on the road for drag tracking, for example, and are willing to sacrifice a little handling to get it. It's a rational choice for that use. I just wouldn't do it because the right tires are back-ordered.

KIS007

It's very annoying when you make a well reasoned argument that is contrary to what I want to do. Kidding aside, your guidance is much appreciated. I was planning on increasing front tires to 245 and rears to 265. Now I am re-thinking my decision. It sounds like you would advise against it.

whoover

Sorry.

Anybody considering changing wheel or tire sizes should have that calculator at the top of their favorites list.

My approach always has been to let that calculator tell me what's rational. If it shows .5% or better, go for it. Otherwise, I wouldn't. The 245's would give you a 4 mm error at the front (axle plane to ground). I'd be more worried about caster changes and other front-end alignment issues than even the rear. That great steering feel is most likely going to suffer a bit. The good news is that it's easily fixed: just get rid of the new tires.

The way I look at it, if a different tire size would make a better AMG, that's what it would come with. Of course, a properly sized plus fitment which preserves circumference and doesn't rub is the exception, but even in that case most of those examples are factory options.

PkB2014

Though he is most likely technically correct. I wouldn't worry. I'm moving to 245 fr and at least 265 r once the OEM tires are done. I would think the added grip would make up for the 1% variance that the traction control might sense. These cars shred tires as is so I'm not worried about wearing out faster either. But I understand what he is saying so there is certainly reason to stay stock size if you want to.

zcct04

This is getting a little thick. The computer doesn't know your speed. It just counts the axle RPMs and then calculates the speed based on the OEM tire size.

Let's look a this realistically. Your new tires have a 10/32 tread depth - about 8 mm. Worn out tires hit the wear bars at 1.6mm tread depth. There's a 6.4mm difference in radius between new and worn out. That's just the normal operating range for the car, and it's almost double the 3.5mm difference in radius between a 255/35 and 265/35 tire. Go for it - it'll look better and you'll probably have LESS traction control intervention with the wider and stickier tire. You'll be just fine.

zcct04

I respectfully gotta disagree with the logic for not doing this.

"Race cars (and even race suspensions for our cars) are much more adjustable both front and back so that alignment can be dialed in with different tire diameters, offsets, etc., but a stock rear end will just be out of alignment, if only slightly."

With all due respect, changing the rear tire diameter will not change camber, caster or toe in any way that I can think of. In what way would it make the rear end out of alignment?

whoover

First of all, we agree on one thing: if a tire size change has unintended consequences, next tire set can fix it with no permanent damage done. And sadly, that will be sooner than we'd like.

But the .5% circumference target isn't mine; it's used by a lot of pros and you can find it lots of places. Second, search on ESP and larger tires and you'll find all kinds of threads. Some are even in Chrysler and Jeep forums. Finally, caster is a front-axle thing. I was talking about it specifically with respect to the fronts. Self centering works because the "kingpin angle" (the angle between vertical and the imaginary line between upper and lower ball joints) subtends the front half of the tire's contact patch. That's why forward motion wants to drag the wheels into a straight-ahead position. If the front tire is taller, the kingpin axis intersects the road farther back, reducing the caster effect for the same caster angle (which can't be changed). It will be a small effect, but probably noticeable, which is what I said.

The rear alignment will also be similarly affected. The camber angle won't change, of course, but because it doesn't the contact patch will change with a taller tire.

These changes are slight at 1%, but this suspension is aligned to very tight tolerances. It's your car and these numbers are small enough that you're not going to have major issues so go for it, if only to see for yourself how it changes steering feel, handling and traction control. Just don't be surprised if you don't get the improvements you're hoping for. Once again, if they were that easy to achieve, the car would come that way.

Anyway, I didn't mean to get into a big debate. As long as folks understand the issue of tire circumference when they replace, I've done what I intended. Of course the decision is the owner's.

CMC-63

Don't have much of a technical input here, but I have been noticing weird traction and handling behaviour after putting on my new wheels.

I have 19x8.5 with 245/35 and 19x9.5 with 275/30, and I was expecting a huge improvement in traction and handling, but the result was rather disappointing. Yes the grip is there more so then before, but the cars handling behaviour has definitely changed, especially the way the ESP reacts.

I was on an empty straight away and decided to see how straight line acceleration has changed. To my surprise the ESP locked up when it usually would not, and put my tail sideways. Although this wouldn't surprise most c63 owners (happens rather often), I am certainly noticing a difference in the frequency of ESP interruptions, especially during faster turns.

YICS NZ

Wat brand tires you have?
I generally only engage esp when its wet. The increased amount of traction is incredible with wider tires.

chris135b

Hi all,


Saw this thread and it is very intriguing! I figured I would give you my experience as I am 2 days into 265s on my 507. I'll try to keep this brief.


Called TireRack and spoke with the rep a few months ago. I told him about the car's rear tires. He mentioned that the company was well aware of the situation with the 255s. If a customer called in and wanted to upgrade, the recommendation was to go with the 265s only (yes, there is a debate on the board here about 275s. Some have them with no issues).


Fast forward and now I have the 265s on the car. Point of reference: Michelin PSS tire; Fronts-235/35/19, Rears-265/30/19. We went driving around yesterday to see what the differences were between the stock Pirellis and the Michelins. We were up on a rather curvy road here in the Tri-State area (for the NYC people-Bear Mountain/Harriman Park roads off of the Palisades).


There is a HUGE difference in grip! I was able to go much deeper into braking zones into the turns and was able to have between 5-10 mph more with apex speeds. Also, "allegedly" there were a few motorcyclists that tried to keep up with me around the roads. I was able to pull away with ease. Both allegedly gave me the thumbs up, said I was crazy and the car was SICK! I made my wife a little "sick" as well from the "alleged" driving yesterday as well. She mentioned the real feel with the Michelins are "Much Gripper than the Pirellis. I imagine it's like the 2013 Softs vs. Super Softs Pirellis for F1. The SuperSofts were usually .3 -.8 seconds faster than the Softs."


We played with Full TC and Sport Mode TC. The only time the ESP kicked on was when there was gravel mid corner and on the exits. Of course, this would be the case. However, I can say that the ESP was not kicking off as much with the 265s compared to the 255s. Even when not necessarily pushing the ESP would not kick off as much around corners. Unfortunately, I don't have the AMG Perf Media package to see the difference in lateral Gs. But the speedo definitely is telling me corners are faster with the Michelins.


It started to rain on the drive home and I only got the ESP going crazy one time. And this included hard acceleration from a stop onto a road where everyone does 70mph in a 50mph zone (87-South onto the Saw Mill River Pkwy). However, there are two variables here: Michelin vs. Pirelli/10.04 in vs. 10.43 in widths. I have a feeling the Michelin rubber is giving the better traction here.


To wrap up: 265s seem to be much better than the 255s even though there is not much difference in footprint. Michelins are hands down much better than the Pirellis on the roads here in the NYC area! ESP is kicking off less with the Michelin 265s vs. the Pirelli 255s. Variances for the Michelin 255/265s per Michelin Specs (http://www.michelinman.com/tire-sele...ires#techspecs): Diameter(25.1/25.3); Revolutions (829/822); Weight (24.7/24.9)


To esses: get the 265s.


Happy around town everyone. Summer is almost here!


-C

KIS007

What is the feedback on increasing fronts from 235 to 245? Are there noticeable benefits? Or is it mostly aesthetics?

CMC-63

Michelin PSS.

I rarely ever turn traction complete off, and leave it either completely on or on sport mode. May have something to do with it, but as I believe most people leave it on sport mode.

Seem to have conflicting results with Chris135b too which is weird, as I don't think the difference in 275/265 and 245/235 should even be that noticeable

bhamg

All positives. If you're not trying to squeeze out the last few mm in tread width IMO 245/265 is the best fitment in 18" and 19" for balanced handling and rub-free daily driving.

whoover

+1 for the PSS. I had them on the C55 and they were amazingly better than every other tire I'd been through. And they were wearing better to boot.

So far I'm impressed with the Contis that came with the C63 (ContiSportContact 5 P). I groaned when I saw them but they've seemed very sticky. Of course, I'll withhold judgment until after break-in, but if they continue to feel as good and have a decent life they'll be winners. (The Michelins have a wear rating of 300 and the Contis 280, but those are rough guides at best.)

Continental was aiming at the PSS with this tire and it would be great if they exceeded it. Time will tell. Do other owners have impressions of the Conti 5Ps?

bhamg

Some people here don't like the Conti's. I put 8k miles on a set and think they're an excellent tire, even surprising me with their wet-weather capabilities. The Conti's performance is light years ahead of the original OE fitment of P Zeros.

K-Mac

Oh the frustration. Performance vehicles and only front and rear Toe adjustment OEM!


We saw the need and were the first company to provide fully adjustable suspension.


Now you can return your Mercedes to factory specs after altering height or tire size. Fitting wider profile tires, fix steering pull and with the advantage also of ongoing adjustment for curb knock damage or being able to alter specs on track days.


Front Camber and Caster, Rear Camber (and extra Toe) adjustment to resolve premature, costly inner edge tire wear, improve traction, directional control along with cornering and steering response.


K-MAC patented design, bolt on kits, no special tools required. Fast, single wrench adjustment, to suit virtually every Mercedes model - Sedans, Wagons, SUV's and Commercials 1968 to 2014.


Proven designs (K-MAC - manufacturing front and rear kits longer than anyone else). Simply fit and forget - and enjoy the new found handling characteristics.


Rear kits - advantages over the alternative "upper link arms with spherical bearing rod ends" - these rigid arms soon pound out causing rattles, squeaking through metal to metal contact. Also to reduce inner edge tire wear they must adjust top of tire outwards. Reducing all important tire to outer fender clearance.


Month of May special FedEx freight deal for MB World members USA/Canada $25 one kit or $35 front and rear.

CarHopper

This thread is way more in depth than it needs to be. We are talking about C63's here that see the road daily for the most part. MOST people who have modded suspensions stop at coilovers/springs and MOST people stop the performance bar at a tune/headers. Yes, some S/C's are out there, but it still doesn't matter. Correct me if I'm wrong, but people here are looking to get off the line a few times on their drive, maybe get in a highway pull or two, and take a few turns with some enthusiasm. Nobody here is going to Leguna Seca with a completely stripped car that weighs 2000lbs worrying about mm's off a tire.

That being said, while I agree with much of what has been posted here it just doesn't matter for the C. I think tirerack has their max difference at something like 4%. Yes, 4% is high, but 1%? You go through that on every set of tires you've ever put on a car unless you change tires like you do underwear.

On OEM wheels just put 265's on the back and 245's on the front and call it a day. On aftermarket wider wheels definitely put 245's if not 255's on the fronts and you can get crazy with 275 or even 285 on the rear. It won't hurt anything for 99.9% of people who are on here. I leave the .1% for anyone that comes along and drops an insane amount of money on the car in terms of making it just off the charts crazy becauseracecar.

Whoover - I understand your logic and good on you for posting up some seriously valuable information... However, it is way more detailed and strict than it needs to be for the people on this board. I'm sure it is useful for some cars on the road.

Ingenieur

Mine was CPO'ed by the dealer with 245/40/18 and 265/35/18 PSS's

Stefj

I have a complet est for pss 1 summer, Like 80% good

255 ans 235 if you want i could sell it to you