Re-trod the 240D

[240D.Bill]

Finally an OEM size for the 240D that meets the load range! And they are under $150. Not cheap by WallyWorld standards but reasonable considering the lack of options. I’ve been diligent in my quest and I’d love to find out otherwise but I think this Nokian is THE only tire that meets the original specifications.

NOKIAN CLINE VAN
175/70R14 C 93/95S

There are still quite a few 175/65,70,75 choices out there but none of them come close to the OEM load index(94). The closest I’ve seen is an 88 and they are all winter tires.

I’ve read just about every thread on every Mercedes forum I could find regarding 240D tires. They were originally a 175R14, a Euro standard which here in the states at least, is no longer if ever used. The current consensus compromises with the 195/70 or 75 for the little 14” rim as the most viable option. I personally think a plus 2 on stock rims is pushing it and there are some who boast 205’s. They are certainly easy to find and tend to be on the cusp of the load range(90/91) needed for the 240D. Nonetheless, it’s a fact that physics play an important part in both performance and safety. I have faith in the engineers who designed the car but maybe that’s just me. I am certain only that I am ill prepared to counter their expertise.

I myself have always run 195/70’s on both my 240Ds and VW T2 camper van, but how many of us have first hand experience driving a 240D with OEM 175R14 94 tires? I’ll bet not but a few. I expect or should I say hope VWNate can chime to share his thoughts and experience. I suspect VW bus/transporter and crowds of other classic European car owners could provide insight and maybe even some additional manufacturer offerings in the original sizes.

As for myself, I’m going to get a set in the next 10,000 miles maybe sooner. I’ll report my observations when I do.

[t walgamuth]

I had some experience with those 175 tires too (old fart here).One element you may not have been aware of is that those original 175 tires were built more sturdily and were rated for more weight than the run of the mill 175 Michelins. They also had a thick rib on the widest part of the bulge in the tire. I love driving a 240 with the original aluminum wheels and wheelcovers and a nice 175 tire. The steering is precise and the cornering grip is very adequate to make good time on a curvey road. The 195/60 or 70 works well too but is not as sublime as the original tires.

I am surprised you can find a 175 tire today....excepting from Coker or some other specialty company....or Europe.

[pj67coll]

What's the big deal? All 123's had the same rims. They just had different sized tires on the smaller lower end of the range (200, 200D, 240D, 230 etc) compared to the upper end, (250, 280, 280E etc). The difference was more due to cost and econnomy than anything else.

- Peter.

[240D.Bill]

Originally Posted by pj67coll

What's the big deal? All 123's had the same rims. They just had different sized tires on the smaller lower end of the range (200, 200D, 240D, 230 etc) compared to the upper end, (250, 280, 280E etc). The difference was more due to cost and econnomy than anything else.

- Peter.

In the US the stock disc wheels were not the same for 240Ds. MY’81/82 had aluminum disc wheels vs. steel. I’ve heard the cost savings argument before and I don’t buy it. It may hold merit in later w123s but there were any number of areas that could have been targeted to cut costs that would have been targeted cuts before the tires and it doesn’t account for the fact 175s were used on all 240Ds since they rolled off the assembly lines.

[pj67coll]

Originally Posted by 240D.Bill

In the US the stock disc wheels were not the same for 240Ds. MY’81/82 had aluminum disc wheels vs. steel. I’ve heard the cost savings argument before and I don’t buy it. It may hold merit in later w123s but there were any number of areas that could have been targeted to cut costs that would have been targeted cuts before the tires and it doesn’t account for the fact 175s were used on all 240Ds since they rolled off the assembly lines.

You misunderstand me. I know 240D's had the smaller tire. My point is that this is not unique to 240D's. It was the case on all the lower end, slower, targeted more towards economy than performance 123's the world over.

But that same chassis also had the larger tires with the bigger more performance oriented engines. This where high speed performance was more significant than fuel economy.

The narrower tire was on the lower end of the range because it emphasized fuel economy over Autobahn ruling performance.

- Peter.

[t walgamuth]

Originally Posted by pj67coll

You misunderstand me. I know 240D's had the smaller tire. My point is that this is not unique to 240D's. It was the case on all the lower end, slower, targeted more towards economy than performance 123's the world over.

But that same chassis also had the larger tires with the bigger more performance oriented engines. This where high speed performance was more significant than fuel economy.

The narrower tire was on the lower end of the range because it emphasized fuel economy over Autobahn ruling performance.

- Peter.

True enough. IIRC There were different width and weight rims depending on model. 5" steel or aluminum plus wheelcover, 5.5" bundt, and 6": bundt. weighin from about 12# up to 19#. Of course early cars had steel wheels. I am not familiar with them as much.

[240D.Bill]

Originally Posted by pj67coll

You misunderstand me. I know 240D's had the smaller tire. My point is that this is not unique to 240D's. It was the case on all the lower end, slower, targeted more towards economy than performance 123's the world over.

But that same chassis also had the larger tires with the bigger more performance oriented engines. This where high speed performance was more significant than fuel economy.

The narrower tire was on the lower end of the range because it emphasized fuel economy over Autobahn ruling performance.

- Peter.

Ok now I understand, you were referring to fuel economy. I’ve have heard others argue they were saving rubber. That would have made since in WWII era but I don’t think the Germans were subject to US rubber rationing. Hehe

Great insight! Thank you.

[240D.Bill]

I find this all fascinating and tend to believe Mercedes didn’t make a habit of ignoring engineering to improve their bottom line. That line of reasoning has an impact on reputation. Anyway, perhaps my crude academic exercise will be of interest to someone. It does matter to some.
As Observed,
1983 W123.123(240D)
Standard Wheel:
A 123 400 03 02 -Aluminum alloy disc 5-1/2 J x 14 H 2
Options:
1) A 123 400 10 02- Aluminum alloy disc 5-1/2 J x 15 H 2 *
2) A 123 400 17 02- Special(Bundt) Aluminum disc 5-1/2 J x 14 H 2
* I don’t know if 15” wheels were an option in the US. They may have been an optional Bundt size. Maybe someone here knows.

Standard OEM tire:
175R14 Radial, Continental TS 77
Tread- 4 plies(2 steel & 2 rayon)
Sidewall- 2 plies, rayon
Treadwear UTQG 180
Traction A
Temperature B
Max Load- 1310 lbs. **
Load index- unmarked but as per max load, 89-90
Max Pressure- 36 PSI
** very close to but still insufficient by 1983 load rating standards where an equal distribution of axle weight is used

I’m no engineer but here is my math and dumb-logic which assumes a regular 4 tire rotation.
My car:
1978 240D
GVWR 4400 Lbs. (front/rear, 2100lbs/2300lbs.)
I use the rear axle spec as each tire will end up there eventually and must be able to support the greater weight.
Max Load Capacity 930 Lbs.
US DOT load indeces,
89= 1279
90= 1323
91 = 1356
92 = 1389
93= 1433

Hypothetically speaking, if the vehicle were loaded to max capacity the load in the rear would be potentially be much greater assuming driver, up to 4 passengers, and an enormous boot for luggage). I used a fudge factor of .6 to account for a conservative load balance shift of 40% max capacity front and 60% rear.

Therefore, Max Tire load= [(2300 + 930F)/2] where,
F=0.6

Max Tire Load= 1429 lbs.
Min. Load index= 93

Most of the All-season radial 195/70 tires commercially available in the US have a load index of 90-91 excepting winter tires in those sizes. I presume winter tires are more robust to resist puncture from chains, ice, and accommodate studs which result in a typically higher load index that I’ve observed.
Technically speaking the stock tires didn’t even meet the minimum DOT standard in 1983 but there is some variance between European and US load ratings between tire sizes. They certainly didn’t apply my armchair engineering but I won’t hold that against them. Still, the stock tire rating for that 175R14 are significantly greater than anything I’ve found excepting the Nokian Cline Van 175/70R14.

[240D.Bill]

Originally Posted by t walgamuth

I had some experience with those 175 tires too (old fart here).One element you may not have been aware of is that those original 175 tires were built more sturdily and were rated for more weight than the run of the mill 175 Michelins. They also had a thick rib on the widest part of the bulge in the tire. I love driving a 240 with the original aluminum wheels and wheelcovers and a nice 175 tire. The steering is precise and the cornering grip is very adequate to make good time on a curvey road. The 195/60 or 70 works well too but is not as sublime as the original tires.

I am surprised you can find a 175 tire today....excepting from Coker or some other specialty company....or Europe.

I would give a fart if I didn’t love hearing from the old farts.
It’s funny that you mention the original 175 because I was completely in the dark as to what tire was used or anything about its specs other than size. That is until 2 days ago when I got a a 1983 donor car. In the boot was the original full size spare that had never seen the light of day. I was puzzled by the very rib you mentioned. Your explanation makes a lot more sense than what I presumed. You’ll probably laugh but the spare covers always seem to collapse in. I thought to myself, “No way! Could it be this is a dedicated spare in which they manufactured the tire to support the lid? Ingenious!” LOL So was it just more rubber or is there a fiber belt in the ridge?

Some pictures for those interested, the ridge is more prominent than the pictures convey but it’s there.

[t walgamuth]

I would hazard the guess it is just rubber. I'd be surprised if it was just for the pressed wood cover, but not very surprised. I would also make my guess that it was there to protect the sidewalls from curb damage.

There was a 14" bundt that come on s class and possibly SLs that was a half inch wider and about 5# heavier. Early bundts weigh about 14#, the wider ones are at least 19#. I know some of this because I used to autocross the 500sec and the 84 280e euro.

[Mark123]

I have the same Continental in the trunk of my '81. The rim looks like it has never been touched. Surprising given the hard life of the rest of the car. I seem to recall the aspect ratio being 78. This was from before we started calling that number out in the sizing. I like the thinner look. Maybe because I still miss my w110 with 185/80 13's.

[240D.Bill]

Originally Posted by t walgamuth

I would hazard the guess it is just rubber. I'd be surprised if it was just for the pressed wood cover, but not very surprised. I would also make my guess that it was there to protect the sidewalls from curb damage.

There was a 14" bundt that come on s class and possibly SLs that was a half inch wider and about 5# heavier. Early bundts weigh about 14#, the wider ones are at least 19#. I know some of this because I used to autocross the 500sec and the 84 280e euro.

I scored a whole set of the standard alloy wheels with new tires and didn’t even realize it until I swapped with my old ones. I couldn’t believe the weight difference. I presume the Bundt wheels are a bit heavier.

[t walgamuth]

Seems like the oe wheels are 11#...?

That is very light, but the result is a creamy ride with a suspension which will cling to the road on a bumpy curve.

[240D.Bill]

Originally Posted by t walgamuth

Seems like the oe wheels are 11#...?

That is very light, but the result is a creamy ride with a suspension which will cling to the road on a bumpy curve.

That’s one of the best parts of driving these. The suspension is like butter. I love it. Here’s a question for you. Bilstein standard or heavy duty shocks? I was going to buy the standard because I don’t want to harshen the ride. The donor I just got had a pile of suspension parts in the back seat still in boxes. Amongst the were the HD Biksteins and it seems a shame to waste them.
The whole car for that matter is in exceptional shape save for the blown head gasket. I’ve never seen a w123 in the northwest without rust. This is the first and it’s a shame because it’s going to wreckers. I may have to take the doors.

[t walgamuth]

I never could see a lot of difference between the standard bilsteins and the sports.