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Old 04-25-2013, 07:40 AM
Kodey52 Kodey52 is offline
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Default Tire size

I have a 2001 cummins 2500. Right now it has 285's which are 33's. how big can I put without having to lift or trim anything? And what difference will I see in mileage?
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Old 04-25-2013, 09:04 AM
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stodg73 stodg73 is offline
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33's are the biggest tire that will not rub. You might be able to go to 305's if your truck is a Sport model as these trucks are lifted 1" by the factory.

The best mileage you will get are from the 33's, there is less rotating mass than with 35's. Unless you go to a bigger rim, like a 20" or 22". Metal is lighter than rubber, so the bigger rim will mean less rubber/rotational mass.
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O.O., 01.5, Dodge, 2500, High Output (H.O.) Cummins Turbo Diesel (245/505), Quad Cab Long Bed (QCLB), 4x4, Sport, Original Bosch VP 44 Injection Pump, 6 Speed/NV5600 Transmission, 3.55 Gears, 105k, currently stock engine, Fram Air Filter, 285/75R16s, Glow Shift Gauges: Fuel Pressure (FP), Boost, Exhaust Gas Temperature (EGT), Oil Temperature, SMARTY@1, Airtex lift pump 19 psi @ idle, 14 psi @ WOT, Propane Injection, 2 Stroke Oil, Intake Air Temperature (IAT) Fooler = Better MPG, Bed Lined, Chrome Nerf Bars, more to come!!

Toys:
'79 CJ5, 258ci, 3" lift, 33x12.50x15, Stock Engine and 3 Speed Tranny
'05 Suzuki, GSX1300R, Hayabusa, All Stock, #3('00 blown engine, '00 stolen, & '05)
The complete live & learn and pass it on by H. Jackson Brown, Jr.
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Old 04-25-2013, 09:46 AM
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Stodg is so right. Lighter the weight mass the better you are for MPG's. But now rolling resistance is based on amount of rubber touching the road and how aggressive the tread is. Narrow the tire and less aggressive the tread then the better the MPG's. Just look at racing slicks. Front tires are tiny and narrow and rear are just wide enough to get enough traction for the HP/TQ but both at without tread pattern and rear slicks weight maybe 20-25 pounds a tire which is really light.

My current setup with 235's I'm right at 62# per wheel (rim and tire)





MPG logs
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2002 Dodge Ram 2500, 5.9L Cummins Turbo Diesel, 5 Speed NV4500 transmission, 4x4, 3.55 Gears, AirDog 150 fuel pump with 1/2" Big Line Kit, Stock Bosch VP44 Injection Pump, Bosch RV275 Injectors +40HP, Edge Comp Performance Box, BHAF (Big Honkin' Air Filter), Stock Holset HX35W Turbo, Straight 3" Pipe Exhaust, Crankcase Vent Mod, High Idle Mod, MPG / IAT fooler Mod, ScanGauge II, 25% Tinted Windows, DiPricol Gauges (Fuel pressure, Boost, Pyrometer), 235/85 R16 tires mounted on 16x7 Aluminum mags (weighing 62#), Custom Fog Lights, Custom Backup lights, Silverstar Headlights, 23-24 MPG

1996 Dodge Ram 1500, 5.9L Magnum V8 Gasoline Engine, 46RE Automatic Transmission, 4WD with CAD axle with 3.55 Gears, Mopar Performance PCM, Gutted Kitty, ScanGauge II, 35% Tinted Windows, 16-17 MPG

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Old 04-25-2013, 09:59 AM
Kodey52 Kodey52 is offline
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So what about if I use 305's with a 20" rim. How would that compare to 285's with a 16" rim when it comes to MPG.
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Old 04-25-2013, 10:16 AM
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You would need to weigh the tires and rims to get the weight. If the weight is comparable to the 285's, then there is no real difference. The rotational mass/weight is the same, just a bigger tire/rim.
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O.O., 01.5, Dodge, 2500, High Output (H.O.) Cummins Turbo Diesel (245/505), Quad Cab Long Bed (QCLB), 4x4, Sport, Original Bosch VP 44 Injection Pump, 6 Speed/NV5600 Transmission, 3.55 Gears, 105k, currently stock engine, Fram Air Filter, 285/75R16s, Glow Shift Gauges: Fuel Pressure (FP), Boost, Exhaust Gas Temperature (EGT), Oil Temperature, SMARTY@1, Airtex lift pump 19 psi @ idle, 14 psi @ WOT, Propane Injection, 2 Stroke Oil, Intake Air Temperature (IAT) Fooler = Better MPG, Bed Lined, Chrome Nerf Bars, more to come!!

Toys:
'79 CJ5, 258ci, 3" lift, 33x12.50x15, Stock Engine and 3 Speed Tranny
'05 Suzuki, GSX1300R, Hayabusa, All Stock, #3('00 blown engine, '00 stolen, & '05)
The complete live & learn and pass it on by H. Jackson Brown, Jr.
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Old 04-25-2013, 11:15 PM
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Here is what my 265's look like on the scales...



Those are about a 2-3 MPG loss...



I'm glad they are wore out and not going to be used any longer.
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Michael Nelson - AKA: Mopar1973Man - Forum & Articles
2002 Dodge Ram 2500, 5.9L Cummins Turbo Diesel, 5 Speed NV4500 transmission, 4x4, 3.55 Gears, AirDog 150 fuel pump with 1/2" Big Line Kit, Stock Bosch VP44 Injection Pump, Bosch RV275 Injectors +40HP, Edge Comp Performance Box, BHAF (Big Honkin' Air Filter), Stock Holset HX35W Turbo, Straight 3" Pipe Exhaust, Crankcase Vent Mod, High Idle Mod, MPG / IAT fooler Mod, ScanGauge II, 25% Tinted Windows, DiPricol Gauges (Fuel pressure, Boost, Pyrometer), 235/85 R16 tires mounted on 16x7 Aluminum mags (weighing 62#), Custom Fog Lights, Custom Backup lights, Silverstar Headlights, 23-24 MPG

1996 Dodge Ram 1500, 5.9L Magnum V8 Gasoline Engine, 46RE Automatic Transmission, 4WD with CAD axle with 3.55 Gears, Mopar Performance PCM, Gutted Kitty, ScanGauge II, 35% Tinted Windows, 16-17 MPG

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