"HR" rated tires - PeachParts Mercedes-Benz Forum

angst · #1 06-10-2002, 11:50 AM

My tires are toast and I am about to get 4 new all around. I need the scoop on the HR rated tire. HR is called for in the owners manual and also at the Goodyear place I stopped by. The shop would need to call around to get some in and they would be more than the regular ones (like $70 each instead of 35 each). The cost difference is pretty big so I would rather go with regular if it would be fine.
Do I have to have "HR" rated tires? The tires on it now are just regular 205/70R14.
thanks
Eric Z
1979 300SD (116.120)

#2 06-10-2002, 12:27 PM

Eric,

"HR" tires are simply "speed-rated" to a specific MPH. If you do not plan on sustained driving at these speeds, the ratings are not necessary.

If memory serves, R-rating is 106MPH, S-rating is 112MPH, T-rating is 118MPH, and H-rating is 130MPH.

"Rated" tires typically handle better with improved braking, traction, and steering response. Most of us don't need the performance of an upper rated tire like "H", "V"(149MPH), or "Y" (186MPH); not to mention the cost involved.....

"Standard" rated tires (R or S) will be fine. I personally prefer Michelin or Yokohama brands.... Most of these are speed rated to "S" anyway, and the price is close to "generic" brands. The last set of Michelin Weatherwise I bought were on sale for $39 each at the local Sears Tire & Auto.

angst · #3 06-10-2002, 01:16 PM

I drive 70-75 mostly on highway. The car is so wound up at 80mph (about 4k rpm) I cant imagine that it will even do 100.
The guy at the tire store said that the "H" tires had a heavier side wall and would be better for this heavier car and better handling like you said.
The word performance is kind of funny when used in the context of this speed demon vehicle.
Does anybody here bother with the heavier tire or does everyone just go with a standard tire?
thanks
Eric Z

andy · #4 06-10-2002, 01:44 PM

Get the recommended tire. When I first bought my car (80 300cd) It had the proper tires, but they were bald. In a pinch I bought a lower quality tire. BIG difference. It was very unstable. I used them for about 5k miles before I bought new ones. The new tires with the stiffer side walls make all the difference in a heavy car. andy

JimSmith · #5 06-10-2002, 01:58 PM

Your car came with 175 SR-14 tires. Mine came with Continentals, and I found them entirely overwhelmed by the mass of the car and my driving style at the time. I changed to 195/70 HR-14 for the higher load capacity and superior handling/braking performance.

As with most things in life you get what you pay for. If you buy Michelin or some other reputable manufacturer's tires, you will likely end up buying a speed rated tire as they generally make tires for multiple markets. In Europe all tires must be speed rated, and you cannot install tires that are not rated above the top speed of the car.

While an H rated tire is good for up to 130 mph, do not confuse the rating to mean you can drive it loaded at 130 mph until the 40,000 mile tread life is worn off the carcass. The classification means you can run there fully loaded for some relatively short period of time, measured in minutes. The real meaning of the speed ratings is a design and quality control classification system. An S rated tire will not pass the H test mainly because of the materials and workmanship practices used in its manufacture. This leads to tires with progressively higher ratings that are more and more structurally sound, as well as precision made. Meaning longer lasting round tires. Less prone to fatigue failures or road hazzard failures, and so on.

At the high end of the spectrum (Z and higher rated tires) you end up with tires not intended to last the customary 30k miles or 40k miles as they tend to favor softer tread compounds to achieve higher levels of performance in cornering and braking. People buying these tires usually accept the tread life loss as an acceptable consequence of very high performance.

Not to confuse you, but the H rated tire from Michelin will usually be made following industry practices for a relatively high performance tire. If you don't use the performance related to the speed, you probably will enjoy the way they stay balanced for a smooth ride, braking and cornering.

If you buy unrated tires, the chances are they are made to S rating standards as and they will provide satisfactory service if they are made by a reputable manufacturer and you are a conservative driver. I would not recommend the 175 R-14 tires though, as they just don't have the strength to control the car.

Good luck, Jim

#6 06-10-2002, 04:16 PM

angst,

I do not know what part of the country you are in. If you are in a hot climate, I mean really hot like Texas or Arizona, you need to pay close attention to the temperature rating on the tire. There is a standard tire rating on EVERY tire sold. The first number is treadwear as a percentage of the wear of a standard tire, the second is traction as a letter, A being the best and the third is temperature rating, again with A being the best.

To get an A termperature rating, you will probably have to buy a speed rated tire such as an H or V. If you don't live in a hot climate, a B temp is okay and you can get this in an S or T rated tires. These tires do indeed have a softer sidewall and will make handling squishy, but if you are on a budget, these are the cheapest and typically the hardest rubber compound meaning they will last the longest.

You can go to the Wheel and Tire forum here on mshop and click on Tire Rack at the top. You can learn alot about tires and how buy them on the Tire Rack sight.

I drive 180 miles per day round trip to the office when I'm not business travelling somewhere (right now I am in Milan, Italy.) I chose to go with T rated tires that I caught at a close out pice at Tire Rack. They are Continental AS tires in 205/65 15 and I bought them for $44. The tires do indeed handle squishy, but they carry an 80,000 mile tread wear warranty and balanced out very smooth. Continentals are one of the few tires using construction methods like the Michelins, which I believe are the best tires you can get, but they have gotten very pricey.

On the Tire Rack site, enter your car make, year and model and it will tell you the size that should be on the car. I recommend that you spend some time researching and find a tire that fits your driving style and budget.

If you want tires that do not have stiff spots and will balance out well, I recommend Yokohamas, Michelins or Continentals. MAKE SURE THAT YOUR TIRE DEALER DYNAMICALLY BALANCES THEM WITH WEIGHTS INBOARD AND OUTBOARD ON THE WHEELS. Many tire stores do it quick and dirty and do a static balance with weights ONLY on the inboard lip. If you let them do this, you can guarantee that there will be a vibration. Stick to your guns and make them do it right. Don't worry about the look of the weights on the outboard lip.

Good luck,

#7 06-10-2002, 09:03 PM

My 300 SDL has Michelin Pilot Sport A/S on it. They seem to be an excellent tire for this heavy car. I was concerned about cornering such a big car but these tires handle it with aplomb.

Maybe it is just me, but I can't see saving a few bucks on my only contact with the pavement. A little like saying I don't need brakes that can stop my car in the shortest possible distance since I don't brake hard

.

I would definitely recommend going to the http://www.tirerack.com site and finding the recommended tire for your car, conditions and driving style. They will give you a selection of quality tires that range from cost concsious to pretty expensive. Then choose the ones that make the most sense to you.

MVK · #8 06-10-2002, 09:55 PM

I dont know what size tires are yours. But I got mine from sears. they are Dudlop HR rated I think A2 sport.
For now I am happy with it. I cant say for trade ware n=because they are only 500 miles old.
I got them from sears on sale a few months back. paid 55 bucks for each tire.( My wifes honda Accord has also HR rated last week paid 81 bucks each tire at BJs wholesale club. That price includes hazard warranty, free life time balancing etc. etc.)

When comes to tire, I will not get anything other than recommended rating. But within that rating I will get the cheapest ones.

Just my thoughts.
MVK

autozen · #9 06-11-2002, 12:19 AM

Eric,

After reading all the posts and all the hype, I'll go with William,s suggestion on SR rated tires. New tire ratings came out about a year ago in the USA (have been used in Europe for about 10 years now) which display the speed rating as well as load rating. The load rating will be a two digit # like 85. Your tire dealer should have a chart showing these load rating values. I would stay within the load rating for safety and hang the speed rating. I've owned a half dozen 116 chassis 300SD's, and they are good units, but you have to ask the question. Who am I going to race? I would also not install Goodyears at the moment until they get their dynamic balance problems under control. Craig Breedlove lives about 20 miles down the road and I had an opportunity a few months back to go to his work shop where his crew works on the Spirit of America and talk with Mr. Breedlove. That's where I learned how much tires expand while moving a vehicle close to the speed of sound. Goodyear is having simular problems at highway speeds at the moment.

Peter

rickjordan · #10 06-11-2002, 04:00 PM

Eric, if you are running on 205/70s then your speedomtere is off. My '80 SD (now given to brother) called for 185/70 H14s, which is a real narrow tire compared to your 205s. Remember, the numbers on tires are width(mm)/aspect ratio, speed rating/rim size. You current tire's width is 205 mm. The side wall is 70% of that in height. So your sidewalls are about 140mm. If the car calls for 185/70. Then obviously the sidewall and overall diameter of the tire would be smaller. I was able to buy Continentals for my car from STS tires. I don't know if you have thise trie chain out your way.