285's On A 2500hd

[MKWL]

I'm looking to put Mickey Thompson Baja MTZ's 285/75/R16's on my truck and wanted some input. First off- how much will they rub? Second- how much will the speedo be off with the 285's as opposed to the stock 245's? Third- does the trans/speedo need to be reprogrammed- if so- how much $$$ is is to do and who can do it? Last- how much of a decrease in fuel economy can I expect to see?

 

Thanks,

Matt

[CdnFire]

for speedometer difference use this

 

http://www.csgnetwork.com/speedocalibcalc.html

 

I have 285/60R18 on my truck and they only rubbed on the mud flaps and air dam so I trimmed them, these are on 18x8.5 rims so they sit out further

[Zembonez]

I'm looking to put Mickey Thompson Baja MTZ's 285/75/R16's on my truck and wanted some input. First off- how much will they rub? Second- how much will the speedo be off with the 285's as opposed to the stock 245's? Third- does the trans/speedo need to be reprogrammed- if so- how much $$$ is is to do and who can do it? Last- how much of a decrease in fuel economy can I expect to see?

 

Thanks,

Matt

7.8% difference. At 60 you are actually going 64.7 - 70 is 75.5

 

As long as you keep that in mind, it's easy. I just figure I'm going 5 over indicated speed on the highway and all is good. I've never programmed for larger tires on any of my trucks and all of the old wives tales about ABS or trans malfunctions were false. If it bothers you that the speedo is off a little get it programmed... otherwise just drive it!

[wellinghurst]

Not reprogramming does affect your odometer also-it won't read as many miles as you are actually driving-not necessarily a bad thing I suppose.

[davzog]

I put 265x70x17's on mine and the speedo is off by about 4%....not too bad, about 2.5 mph at 60 mph

 

I went tot he Chevy dealer to have them reset the computer for the difference (for abs purposes) and they could not do it, they said.

 

I have a Blackbear tune coming, so I will get it done then...

[Judge Z]

I´ve 285/65 R18 on my 08 Duramax and doing nice 100 mph on

German Autobahn. Sometimes !!

Don´t like to push the truck always in that way, 1,500 rpm at 65 mph are just o.k.

[hotbread597]

stratosman I thought that getting your computer reprogrammed by a custom tuner made your speedometer correct so that the miles add up?