# CTD tire pressure: Where's the sweet spot??



## GlennGlenn (Nov 27, 2015)

I've been playing with the tire pressure on my 15 CTD with OEM tires. Have found that as little as 2 lbs in each can greatly affect mileage and ride quality/feel. Took delivery at 34 in all 4 which aggravated me and had to stop and get the recommended 38 in each one. Problem is, as soon as I drive, the pressure on the DIC shows 4-6 greater in each tire, making them feel " hard" . 

So, what is my sweet spot based on fuel load, weather, passenger load etc.? I've found that starting each tire at 38 ( car at rest overnight in garage, cold tires ) is a little low. I went up 1 lb in each to 39 which within 10 minutes of driving takes them to about 42 on the DIC and this is where I feel the car does best without too harsh a ride and gives great mileage too on DIC. Went to 40 cold at rest and while driving it goes to about 44 which for me is a bit harsh.

whats your sweet spot?


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## IndyDiesel (May 24, 2015)

I run 39 psi cold and that seems to work well. 38 psi is what is on sticker on door jamb. I don't like over inflated tires I think it does ride harsh.


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## pandrad61 (Jul 8, 2015)

i run 42 psi cold and when they heat up im at 44. i want hot 44 since it gives me a more responsive feel.


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## MP81 (Jul 20, 2015)

Looking at Fuelly, it appears I run 40psi in the winters, and 46 psi in the FuelMaxes.


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## GlennGlenn (Nov 27, 2015)

pandrad61 said:


> i run 42 psi cold and when they heat up im at 44. i want hot 44 since it gives me a more responsive feel.



I can do that on FL roads, but when in IL, the 44 would beat you and the car.


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## pandrad61 (Jul 8, 2015)

Yah even our worst roads aint too bad here in florida,


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## GlennGlenn (Nov 27, 2015)

MP81 said:


> Looking at Fuelly, it appears I run 40psi in the winters, and 46 psi in the FuelMaxes.



For my roads etc., 39-40 cold appears optimal as it rises once I start driving ( get em hot). Manufacturer recommended at 38 seems a touch low.


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## Robby (Mar 1, 2013)

I keep mine @50.....NW Chicago burbs......

Two reasons: 1. best mileage
 2. The high pressure keeps the short sidewalls from collapsing to rim edge on a hard edged bump.....reducing the chance of rim or tire damage.

Rob


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## obermd (Mar 3, 2012)

Your sweet spot will be somewhere between the 38 PSI on the door placard and 51 PSI on the sidewall. Try at various pressures and look for where you like the performance/comfort.


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## CruzeDan (May 17, 2015)

39 or 40psi cold does it for me.


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## Fockewolfe (Jul 27, 2015)

I run 40 'errywhere.


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## diesel (Jun 8, 2013)

Interesting thread. I have thought about this a good bit but haven't done a whole lot of experimenting. Right now I am at 39 cold IIRC. I see 41-42 PSI on the highway. Seems to be a good balance of ride, handling and fuel economy. I may bump that up a lb or 2.


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## BU54 (Nov 24, 2014)

diesel said:


> Interesting thread. I have thought about this a good bit but haven't done a whole lot of experimenting. Right now I am at 39 cold IIRC. I see 41-42 PSI on the highway. Seems to be a good balance of ride, handling and fuel economy. I may bump that up a lb or 2.


That's what I keep mine at. It seems to be a nice balance for MPG and handling.
Sunday it was 80*F-ish and pressure was 44.


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## MilTownSHO (Oct 9, 2013)

Keep mine at 38


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## KpaxFAQ (Sep 1, 2013)

I run 45psi cold here, in the hight heat of summer it will peak at 51 hot.


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