Last month, I purchased a new set of Khumo P205/70/14 tires to replace the Remington Emerald P205/70/14’s that were on the car (116.120) when my son had his April, 2006 accident on SR 99 near Kingsburg, California. These tires were flat-spotted from pre-collision braking and needed to be replaced.

When I put the Khumo’s on the car, I immediately noticed a pull to the right that I didn’t have with the Remington’s…Of course, the tire shop blames the alignment, which seems to be the usual response, but I have the car aligned every (6) months, so I always have a report handy. However, I just didn’t have the time to deal with the tire issue right then and there, as I am currently working Monday through Friday, 6:00am to 6:00pm, so, I decided to just drive the car until the following weekend and address the matter on my days off.

I drive this car 110 miles a day (round trip) to work, (5) days a week and I check the mileage on each and every tank of fuel and each and every quart of oil…so needless to say, I was floored when my mileage dropped from my usual 28.0 mpg to 18.0 mpg!!!!!

I checked tire pressure and they were set at 35 psi at all four corners, so I upped the pressure all the way to the sidewall specification of 44 psi. This made no change in the pull or the mileage whatsoever. The strange thing is the car felt like the parking brake was on the entire time that I was running the Khumos.

The next Saturday, I took the car in with a copy of the alignment report and asked that they install a different set of tries on the car. We ended up putting a set of Dunlop Citation 205-70-14 whitewalls on the car and I had them set the pressures at 40psi on the drive axle and 35psi on the steering axle.

Immediately, the pull disappeared and the mileage returned to 28.0mpg again, where it has remained for the past (7) tankfulls.

I thought you all might find this interesting….Robert

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

something was dragging. perhaps you have a stuck caliper? no way tires can make a 10mpg or 33% loss in fuel economy!

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Well,

They did.....

My Dad, an old NASCAR crew chief said they have seen bad tires create a 'roll' where the tread meets the road that creates significant amounts of rolling resistance and a dramatic reduction in fuel economy. Larry at Gross & Stevens in Visalia, California, reported seeing similar reductions in mileage based on tread/belt separations (defects) in new tires recently, especially those made in China, like the Khumos....FWIW....Robert

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Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

so have you replaced the tires and revalidated the fuel economy over a statistically significant (say at least five) number of tanks?

If not, then it is all speculation.

Let me get this straight... the car was in an accident, the tires were replaced, but the alignment was not re-checked. And youre trying to not blame the alignment? After an accident and tire replacement, that would be the first thing Id do to the car.

It seems that the kumhos and/or their tread design did have an effect... and alignment was not effected (this was all differential analysis though, not a real set of numbers from an alignment rack) but a bad tank of fuel could have every bit as much effect, if not more, than a high RR tire.

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

Yes...

I burned a couple of tanks (all from the same supplier) on those Khumos and I burned (7) tanks on the Dunlops....

The alignment was done right after the car was put back on the road in July, 2009. I had the car inspected and re-aligned (like I do every 6 months) in January 2010.

But get this....the Khumos looked funny. They had a buldge where the tire met the road that the Dunlops did not have and they looked low on pressure, even when inflated to the sidewall specification and I confirmed this with multiple guages...Robert

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

bulges? weird, they must not have ratings for the weight of this car.

Sure would be interesting to swap the right side tires for the left side tires to see if it pulls in the opposite direction.

We did swap LF for RF and it pulled the other way...Robert

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

The rating of the tire was far in excess of what the vehicle weighed. It was just a bad set of tires....

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

10mpg loss due to a set of tires is impossible, if you compute the amount of extra energy being used to consume that much more fuel, the amount of heat in the tires would be insane.

With my michelins I get about 22-24mpg with them at 32psi, with them around 41psi I get about 25-26mpg. With my soft Yokohama Snow tires I get about 22-23....but I run them around 30psi.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Unless they were virtually flat I cannot imagine 10 mpg difference under any circumstances.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I can not see the tires causing a 10 mpg drop. As indicated previously something is dragging, somethings is leaking, or somebody's is siphoning.
You do not work in Stockton ?

Good Luck,

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Gary
Experience is something you get, Just after you needed it....
'99 E300 295K, '83 300D 220K, '75 240D 185K sold
'80 MCI Bus Conv DD 6V92TA, w/4 cyl. Kubota diesel GenSet 12.5KW

Tires CAN cause that much difference.

Please factor in the "pulling" due to the defective tire. Frictional loss plus a loss due to power steering pump energy... it all adds up.

I've seen close to that difference in MPG with a change. Never that much though.

oh yeah, I can certainly see huge fuel drops if the tires were defective and causing the vehicle to pull seriously. I just can't see driving any appreciable distance in that condition, to let the economy show up! I'd not make it out of my neighborhood like that, before I called a tow truck and had my car returned to the store for new tires!!!

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Power steering pump energy? The power steering pump does nothing at highway speeds.....you never move the wheel more than 1" anyways.....

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)