Camping Addict Posted June 1, 2015 Share Posted June 1, 2015 2011 F250 6.2 gas lifted 4" on 35" tires. Just changed out the stock 373 for 430. Dealer said my 35" tires reduced my 373 to about 340 and a 430 would put it about 410 so I did it. Put 300 miles on it (hiway) and the mpg jumped from 12 to 14.5 hand calculated I guess cause the engine is not working so hard.. Happy about that. I know this sounds unbelievable but I punched it at an intersection and my jaw dropped open!! The acceleration has been cut drastically!! Went from pretty snappy feeling to a DOG. I'm wondering if they did something to the computer when they reprogrammed it for the lower gears for the speedo? Maybe a tuner is the next step? Thanks for any input. Quote Link to comment Share on other sites More sharing options...
fordmantpw Posted June 1, 2015 Share Posted June 1, 2015 Was it snappy after the 35" tires? Because those things will zap power, even after correcting the gears. They are heavy and require a lot more power to get them rolling. Quote Link to comment Share on other sites More sharing options...
Camping Addict Posted June 1, 2015 Author Share Posted June 1, 2015 Yes it was snappy before. Been running the 35" tires and 373 gears for 33K miles. Maybe it will be better when the computer re-learns my driving style? Quote Link to comment Share on other sites More sharing options...
fordmantpw Posted June 1, 2015 Share Posted June 1, 2015 Yes it was snappy before. Been running the 35" tires and 373 gears for 33K miles. Maybe it will be better when the computer re-learns my driving style? Hmmm, strange. Re-learning by the TCM may help a bit. I would expect it to be a bit more peppy with 4.30 over a 3.73. Could be as simple as a bad tank of fuel, too. Quote Link to comment Share on other sites More sharing options...
92merc Posted June 1, 2015 Share Posted June 1, 2015 Was the speedo ever corrected for the larger tires? Quote Link to comment Share on other sites More sharing options...
akirby Posted June 1, 2015 Share Posted June 1, 2015 Maybe they put in a 340 instead of a 430? Quote Link to comment Share on other sites More sharing options...
theoldwizard Posted June 2, 2015 Share Posted June 2, 2015 2011 F250 6.2 gas lifted 4" on 35" tires. Just changed out the stock 373 for 430. Dealer said my 35" tires reduced my 373 to about 340 and a 430 would put it about 410 so I did it. Put 300 miles on it (hiway) and the mpg jumped from 12 to 14.5 hand calculated I guess cause the engine is not working so hard.. Happy about that. I know this sounds unbelievable but I punched it at an intersection and my jaw dropped open!! The acceleration has been cut drastically!! Went from pretty snappy feeling to a DOG. I'm wondering if they did something to the computer when they reprogrammed it for the lower gears for the speedo? Maybe a tuner is the next step? Thanks for any input. No speedo gears anymore. Everything is electronic. Did the dealer re-calibrate the PCM and the dash for a different rear axle ratio and tire size ? Quote Link to comment Share on other sites More sharing options...
Camping Addict Posted June 2, 2015 Author Share Posted June 2, 2015 Yes Quote Link to comment Share on other sites More sharing options...
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