Jasonoff

So, according to Continental they use the 235/35R19 Z XL (MO) FR TL ContiSportContact 5 P for the OE 19" front.

The MO fitment is Mercedes-Benz specific and has a reinforced sidewall but here's the kicker which is a little odd IMO. They do not list the "actual" upgraded load rating rating on the sidewall. They list the standard load rating with the MO specification.

Read these top to bottom
There was more info in the email trail but I think this is enough to set things straight and kill the unknowns.

Tread Depot

Jason - This is the link to the data page for your OE Conti's - Note they do carry a load index of 87 but carry the same max load rating of 1356lbs that the 91 rated tires do. Interestingly the 18" OE Conti's carry a 95Y up front and a 94Y in the back. Either way the Pilot Super Sports will work in the 235/35R19 and 255/30R19, as they are rated at the same max load as your OE Conti's.




http://www.conti-online.com/generato...tasheet_en.pdf

Jasonoff

It's weird how they do this since 1356 is still under the required (1521) MB spec. The custom MO rated tire, which is different than the standard non MO rated tire does in fact have a reinforced sidewall which has been approved by MB so it's likely safe to assume they are within the 95 (1521) required spec.

I can't say the same for the PSS though.

Tread Depot

Either way they list the max load at 1356 pounds, which matches up to a 91 spec load index.

gthal

I don't know that it is "safe to assume" that the extra reinforcement brings the load rating to 1,521. Continental actually states that the max load is 1,356 for the OEM tire as noted by Tread Depot. The way I interpret this is that it means the Continental has a rating of 87 rating (which is less than 1,356lbs load) but the reinforcement likely brings it up to 1,356. If the tire was an 87, it would not carry a 1,356 max load. So, the car is not coming with 1,521 load tires from the factory.

Regardless (although this is a very good debate), it is largely academic as the load per Continental is the same as the PSS so both will work.

Jasonoff

MB requires a load rating of 95 in the front. They contract Continental to make custom tires for them with the MO rating.

Do you really think MB would install a tire as a factory option that can't handle the required load index of 95 (1521)? I would say it's safe to assume because if MB was shipping the car with under rated tires they would have quite the lawsuit on their hands if anything were to happen, cough, cough, Firestone...

The OE 18" Pirelli is a 95

gthal

Yet Continental publishes the max load rating for tires noted as Mercedes Benz specific tires at 1,356

The published max load for 18" options is higher than the 19" tires. So do you not believe the guy from Tread Depot who says the OEM Continental tires are only 1,356 max load even though Continental publishes the same figures for tires they also designate as MB OEM tires?

Why would Continental publish the 18" tires with the correct 1,521 max load rating but mysteriously publish specs for the 19" OEM tires (that are also NOTED as MB OEM tires on their website) with a lower max load rating but "secretly" reinforce the tires but then do not publish the correct rating (even though they publish correct specs for the 18" tire)? Also, ALL tires rated as XL are reinforced by definition so even though Continental mentioned that to you in their correspondence it doesn't necessarily mean much... all XL tires are reinforced.

Continental notes the Mercedes tires in 235/35-19 size as 87** load rated. An 87 rated tire would be LESS than 1,356. Therefore, logic would suggest that the ** is why a tire that SHOULD be less than 1,356 max load is, in fact, rated as 1,356 max load... as published by Continental themselves AND noted as a Mercedes tire. Lastly, if you re-read the Continental correspondence, they do not once confirm the 19" tire is 1,521 max load. They actually said the 87** is the load rating the tire would have if it were a Y speed rating only. That doesn't imply the tire is rated beyond the 1,356 load that is published by them. I'm not sure where you are getting the conclusion that the MB OEM Continentals are reinforced beyond their published specs from the correspondence you quote from Continental.

I'm not suggesting that MB ships the cars with underrated tires, I'm suggesting that for the 19" wheel, MB is shipping a tire that is rated at 1,356 and that is all the car requires. I'm not also suggesting that I'm necessarily correct... I'm just collecting what I see as published specs (corroborated by Tread Depot and Tire Rack) and coming to a conclusion. I haven't seen anything yet in this thread to convince me I'm wrong... but, hey, maybe I'm wrong... it has been known to happen

Jasonoff

It's very sketchy I know but they're saying they don't list the "actual" load on the sidewall for the modified MO model.

It has nothing to do with believing someone or not. The spec says 1356 in the pdf for the "base" tire (There's 7 options in that size). The MO rated tire is made specific for MB and they don't list the "actual" load. Why? No idea

Another question I don't know the answer to, sorry. I can loop you in on the email trail I had going with Continential North America so you can ask them yourself if you'd like. PM me your email address and I will cc you.

You are correct. They did not confirm which was a little sketchy if you ask me. They just confirmed the MO model is modified and has a different load rating that's not listed.

More from the email trail (maybe I should have just posted the whole thing but it was in this stupid form style format)
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They list a spec for the base tire. The spec for that base tire is lower than what MB requires. They do make a custom MO tire that is MB approved but the specs are not published. So, again, if you'd like to continue with the questions I'd be more than happy to fwd to you the manufacture who makes the tire.

Bottom line... if MB says they require a load index of 95, anything below that is under rated. I don't think it can get any more simple than that.

With all that being said, given the GVWR of the car is 1120KG (2470LBS) a 1365 load rated tire on all 4 corners should be absolutely fine. I will be going with the PSS myself regardless of the rating...

bluejae

just found this thread... i've gone through a few sets of tires and i didn't even think about load rating... i thought if it was XL it would be fine...

where it starts getting confusing for me are the ones that are the same load rating numbers like 93... but one of the tires says XL... i wasn't sure how to figure that out...

AMG Boost

Just looked and my front 235/35/19 MPSS are 91Y. I have tracked these tires with no problems so far....

Ingenieur

Load rating is pressure dependent
These are for illustration, too lazy to look up the table
They are the same for all mfgs
Say the oem 235/40/18 95y xl is rated at 1400 lbs at 39 psi it may be 1550 at 41
Low load 4 passenger vs high 5 passengers plus luggage
The oem 235/35/19 91y xl may be rated 1400 at 41 and 1550 at 43
Or whatever
That is why a lower LI can carry the same load

Oem 18's are 95/94 xl F/R
I have 245/265 they are 97/97 xl iirc so I can air down a few psi and achieve the same load rating with a better ride