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I have a tire and wheel insurance policy, but the inconvenience is getting excessive, and so is the stress that it could happen at any moment again and derail my travel.
Does anyone have any recos for non-run flat 19” tire and wheel combos?
It might also help to know where you are and where you've been driving and on what kinds of roads. Also are all of your damaged rims due to blowouts or have you hit any curbs or something else or is anything else going on? Have you had a problem with slow leaking tires? That's a LOT of blowouts! I haven't had that many or that many damaged rims in over 50 years of driving.
It might also help to know where you are and where you've been driving and on what kinds of roads. Also are all of your damaged rims due to blowouts or have you hit any curbs or something else or is anything else going on? Have you had a problem with slow leaking tires? That's a LOT of blowouts! I haven't had that many or that many damaged rims in over 50 years of driving.
I agree with this. Please also list what pressures your tires are being filled. I’ve never had a blowout, or bent a Mercedes rim. I do keep my pressures on the higher side which also reduces the rear tire wear a little bit. Also knowing to keep pressures proper as seasons change is very important. Pressures can swing ten psi or more on a hot day with a cold night. I live in an urban environment with plenty of terrible streets.
Thank you everyone for your quick responses. Here is all the info (FYI all blowouts have been on the front wheels so that's all I am providing details on):
Front wheels: 19" AMG 5 spoke rims (picture attached)
Front tires: Contintental ProContact GX SSR 245/49 R19 98H M+S Extra Load
Current Inflation: 35 psi cold
I live in CT. Got the car at the end of 2019.
Blowout 1: Passenger side. On a residential street in Norwalk, CT April 2021 going prob 30 mph. What I hit I wouldn't even call a pothole, and it wasn't even the size of the tire, i.e. the tire was wider than the hole. Cracked the rim.
Blowout 2: Driver side. I-84 E outside of Danbury, CT July 2021 going about 70-80 mph. Wasn't a pothole, more like the top layer of asphalt delaminated and was absent and there was a dip.
Blowout 3: Driver side. I-91 N near Cromwell, CT March 2022. Similar speed and road status as Blowout 2.
Blowout 4: Driver side. Hutchinson Parkway S near Scarsdale, NY April 2024. Similar speed and status as Blowout 2. Bent the rim.
Additional Incident: Passenger side. Middletown, CT city street going 15-30 mph March 2024. Hit a true pothole. Put a bubble in sidewall and bent the rim which was a recently replaced rim.
I don't hit curbs. I keep an eye out for potholes. I have been driving for almost 40 years, and for at least 10 of those with run flats on various cars: Mini, Audi, MB. And with those I have hit a lot of potholes with no blowouts. I have heard from the local Mercedes dealer and an independent eurocar shop that they see a lot of this with MB and BMW, but this seems more than occasional bad luck.
Honestly I have no idea! I once hit a curb (an island in the middle of the road) head on in excess of 60 MPH in a 440 powered Challenger and it didn't do nearly that much damage. It put a big dent in the rim and IIRC it cut some of the cords in the tire so that it bulged out on one side when I reinflated it but it did not tear or burst the tire. The rim was out of round but was absolutely irreplaceable so I put another tire on it and continued to use it for several more years. I have never seen a tire with one tear, much less two, like that. The only thing that I wonder about is if the tires you have have VERY thin sidewalls that might make them overly susceptible to impacts. Did you talk to your tire dealer or insurance adjuster about it and what did they say? They would probably know better than anyone else about similar incidents.
I think that I would also contact the tire manufacturers and send them photos and get their take on the damage.
Bought a 2021 CLS 450 with 20" AMG rims (staggered). Tires: Continental run-flats 245/35/20 and 275/30/20 rear. Checked tire pressure and adjusted them to specs behind fuel door.
Got a left front tire failure in 3rd day. It was a baseball size bulge on the side. No damage in rim. Tire dealer and MB dealer and everybody else I talked to said I made a gravely mistake,
those tires need to have min 42 PSI front and 47 PSI rear. To be honest the cornering with those pressures is superb, but I lost a lot of convenience. Thinking seriously
going back to 19" setting or even 18" and without staggering. Comments?
Bought a 2021 CLS 450 with 20" AMG rims (staggered). Tires: Continental run-flats 245/35/20 and 275/30/20 rear. Checked tire pressure and adjusted them to specs behind fuel door.
Got a left front tire failure in 3rd day. It was a baseball size bulge on the side. No damage in rim. Tire dealer and MB dealer and everybody else I talked to said I made a gravely mistake,
those tires need to have min 42 PSI front and 47 PSI rear. To be honest the cornering with those pressures is superb, but I lost a lot of convenience. Thinking seriously
going back to 19" setting or even 18" and without staggering. Comments?
I have the same wheel setup in my E-coupe (it shares most components with the CLS). I upsized the aspect ratio by +1. So now the size is 245/40/20 & 275/35/20, no rubbing, plenty of clearance and the car rides great for 20 inch wheels. Also, it provided improved protection from potholes and what have you.
oh yeah, and I ditched the Michelin PS4 ZP runflats with non-runflats and the difference is night and day.
You essentially have a few things working against you. The roads are getting worse in many parts of the USA, because the cities don't actually have the funds to maintain all their roads. They get federal grants to build new roads, but don't have the money to maintain all those roads afterwards. It's a death spiral.
Cars have also gotten heavier. Your CLS weighs around 4300 lbs, whereas something like a Mini in your list weighs around 3000 lbs. Bombing through a pothole with over 1000 lbs weight difference will have vastly different outcomes. In addition, back in the days, normal cars had 16" or maybe at most 17" wheels and plenty of tire sidewall to protect the wheels. Now car manufacturers put 19", 20" or even 21" and 22" on normal commuter cars for optics. These come with low profile tires that have very short sidewalls. It doesn't take much to blow one out or damage a wheel.
Lastly, wheels come in different grades. Most wheels are cast. Cast wheels require lots of material to make them strong, however that also makes them heavy. A strong cast wheel is very heavy and that affects fuel economy etc. so they make them lighter, but that reduces their strength. Cast wheels are cheap, so most normal cars have cast wheels. Even the so-called AMG wheels that you have are cast. Stronger wheels are forged and you find them on true AMGs and other performance cars. Forging makes them strong, so they don't need as much material and can therefore be made much lighter w/o losing strength. Doesn't mean that a forged wheel is stronger than a comparable cast wheel, but the forged wheel will be much lighter to have the same strength as a comparable cast wheel. However, forged wheels are very expensive. You get what you pay for. A set of AMG forged wheels easily costs $8k to $10k or more.
I have forged AMG 19" front 20" rear on my C63 and never blown out a tire or cracked a wheel. Neither have I on past performance cars with up to 20" wheels. I did slightly bend one of the current wheels and bubble the tire, because I hit an inch of raised pavement that I didn't see. It only slightly bent the lip of the wheel, though. No crack. A testament to the strength of forged wheels. The tire had to be replaced, but I'm guessing most cars would have damaged a tire and/or wheel if they hit the same thing. Maybe not an SUV with huge tires and tall sidewalls. That's basically where we are in many places of the USA. You have to drive a pickup truck/SUV with lots of sidewall on the tires if you live in places with very bad roads. It's only gonna get worse. 19" wheels on a commuter sedan isn't a very good idea these days.
Last edited by superswiss; 06-19-2024 at 01:59 PM.
Some of the worst roads are in states with the highest taxes.
A lot of those states have intricate networks of toll roads.
Toll roads in those states have been around long enough to be fully capitalized, that is fully paid off, mainly from the tolls imposed since their opening.
The early promise, is that once the original capital outlay was fully reimbursed, the tolls would be a small fraction of their pre payoff amount.
But, what actually happened was that over the years, toll attendant wages increased to the point of replacing the capital cost, and more.
So now most if not all of the toll revenue goes to the attendants.
None left over , or not enough left over to pay for minimum maintenance or replacement.
There is a moral to the story, but I am guessing the residents of those states won’t want to hear it.
I am going to do my best to never be on any of those roads, in any of those states with my favorite MB.
I've had my 2019 CLS450 for 22 months (35,000 miles) , it was factory fitted with 20" AMG wheels with Front: 245/35 R20 Run Flat - 38 PSI & Rear: 275/30 R20 Run Flat - 38 PSI. I've used Michelin Pilot Sport 4, Continental 6 and Pirelli PZ4, all pretty similar performance.
In that time I've had cracks in all 4 wheels from hitting potholes, also had 8 tires replaced due to damaged sidewalls, sometimes the same incident as the wheel cracks, sometimes the tires split with no evident wheel damage. One wheel repairer said "most of my jobs are repairing these Mercedes alloy wheels, worst alloy I've ever welded".
After spending over £2000 on wheel repairs and tyres I've decided enough is enough and bought a set of 18" Starlight Silver Alloys from MAK with Michelin Pilot Sport 5-275/40 18 and 245/45 18. Cost was approx £1600 for the wheels and tyres, not bad as I was just about to have to replace 3 tyres due to wear which is around £800.
After 5,000 miles use the new wheel tyre combination is a revelation, much more comfortable ride with the noisy crashing over bumps and potholes gone and no fear of any pothole damage with the 40 and 45 aspect ratio with nice fat sidewalls I now have, same as my previous CLS that I did 220,000 miles on the same roads with no hint of any tyre or wheel problems. My advice is if you can you should switch to 18", saves money in the mid term and gets rid of the inconvenience of constantly being at the wheel /tyre shop, plus a better ride and you can choose a new look
MikeJohns, I think you are right on the money. What you did is the way to go. You may loose the aggressive looking 20' setting has, but there is so much more to gain.
Why -21 CLS has 20" setting? In this country importer (MBUSA) decides the specs they order from factory. Then they tell customers that "this year CLS comes from factory with that and that"
They let you understand this is the only way they are made this particulate year. That's not simply true. 2021 model was made with three alternate wheel settings. In Europe,
customer is able to order whatever is listed factory spec sheet. Unfortunately, we don't have that luxury in the USA. Even worse, the decisions are made by importer's marketing department,
not experts.
I will do the same with MikeJohns and change the wheel setting to 18". There is a very handy calculator on-line, where you can simulate different rim/tire combinations, their
different measurements and effect to speedo. click: https://www.miata.net/garage/tirecalc
Talking about road quality, our roads in Arizona are very good, probably the best in nation. It's why because in this area we never have temps below freezing point and very little rain.
Potholes are very rare and it looks like no money is saved when maintaining roads and building new ones.
All that said I'll jump to 18' setting asap.
Thanks kilovictor, good to know someone else shares my ideas. I couldn't access that link but if anyone is looking at the different tyre sizes the petrol cap shows the options for 18", 19" and 20", as they are standard fit I'm assuming the speedo and fitting in wheel arches is OK for all listed combinations, certainly my 18" have not changed the speedo and fit perfectly, ride is better, handling perhaps a tiny bit less sharp but I don't care as to me the CLS is a GT not a sports car. Original 20" wheels
Original 20" at the top, petrol cap showing standard sizes and new 18" at the bottom.
Thank you MikeJohns for the pics. Looks like you have different sticker behind fuel door. Here is a pic of US one.
Also enclosing a pic of My CLS 450 rear wheel with 275/30/20 continental tire.
Thanks for reposting the link but I still get "Forbidden", perhaps because I am in the UK?
Nice to see a white CLS, most of ours are grey with the rare exception with a bit of colour like mine, took me a year to find the red with beige interior as most are grey on grey.
Thanks to this thread, I switched to 19” wheels right away on my newly purchased CLS 450.
I drove around 1000 km on the 20” before switching, and boy is this the same vehicle !
Handling is a little bit of, but the car is more of a grand tourer now than the sporty aggressive stance it took before. I think it suits the Designo interior much better.
P.S. I explore the option of upsizing to 245/40R20 and 275/35R20, but backed off at the fact I can’t change the speedo calibration easily, and that I might have less suspension travel before causing damage. Not saying it won’t work but that was my preference. Putting the 20” wheels up for sale.
Before - 20” - 245/35(F) and 275/30(R) After - 19” - 245/40(F) and 275/35(R) After - 19” - 245/40(F) and 275/35(R) Designo Interior
I am in the process of going to 18 x 8 rim size, but can't find exact offset values. Owners Manual won't help. There are some information bits
here and there, but where can I find Mercedes specs for offset? (2021 CLS 450)
Thank you for your answers,
Hi Kv, not sure if it helps but these are the wheels and tyres I purchased which fit perfectly. The rear is 9,front is 8. The company did supply two offset "washers" but they said they might not be needed, they were to make sure the brake disc cleared the new wheels. I did a test fitment without the washers and the front wheel was closer to the discs (approx.5 inch) than with the 20" but not enough to worry about even with a bit of heat expansion and after several thousand miles there is no sign of any rubbing, touching and the car feels perfect so I'm not going to fit the washers.
05-05-2024, 08:14 AM
