Effects of bigger tires on transmission

[buubba429x]

I have a 2003 Ford Explorer NBX. It came stock with the 17" alloy wheels and 245/65/17 tires. I needed to replace my tires and recently came across a deal on a stock set of Jeep Rubicon 16" alloy rims with 245/75/16 Goodyear tires on them with excellent tread for $600. The set came with 5 rims and tires, with the brand new spare mud terrain is going for about $300 alone, so I had to jump on it. I did however notice a slight change in the way the truck drives. The speedo is probably off by a couple mph and I feel like the transmission shifts aren't as smooth as stock, which I somewhat expected. Are the effects of the slight jump in wheel size enough to warrant an ecu reprogram for the bigger tires so that the speedo is accurate and the tranny runs smoother? I also have another set of stock rims/tires that I put on for the winter. If so, I'd have to do it twice a year once for the bigger set of rubicons and then again in winter to reset it back to stock. The dealer wants at least $100 to reprogram each visit. The truck has 99k on it. Some experiences/opinions welcome.

 

[HiImBrian]

I haven't felt any differences in my transmission going from 28" A/T to 33" M/T tires. From my understanding, there have been PCM updates since production that will help smooth a lot of things out. You could also go with a tuner that would allow you to adjust accordingly whenever you want to change anything.

Read through this thread and learn a little about it: http://www.explorerforum.com/forums/showthread.php?t=270842&highlight=SCT

James at Henson Performance has been great to a lot of guys on here. I haven't had the chance to do business with him yet, but am looking forward to in the near future. Here's his website: http://www.hensonperformance.com/Productsftel.html

I'm sure some other guys on here will chime in soon, and they'll know a lot more about it than me...

Last but not least, Welcome! Don't have many NBX owners on here, so feel free to show it off

 

[LONO100]

going to a larger than stock size tire will throw off your speedo which will in turn throw off the shift points of your tranny (auto). if you will be switching back and forth between wheels with differing tire sizes, you will ultimately save money by buying a superchips tuner that will give you the ability to program the tire size you are using. this will calibrate your speedo accordingly, and help your tranny shift better. ive been tinkering with this idea myself and probably will go for it at some point this summer. you can also look into one of these:

http://www.4wheelparts.com/Performa...c=74&t_s=33&t_pt=5085&t_pl=4008&t_pn=SUP33002

 

[buubba429x]

going to a larger than stock size tire will throw off your speedo which will in turn throw off the shift points of your tranny (auto). if you will be switching back and forth between wheels with differing tire sizes, you will ultimately save money by buying a superchips tuner that will give you the ability to program the tire size you are using. this will calibrate your speedo accordingly, and help your tranny shift better. ive been tinkering with this idea myself and probably will go for it at some point this summer. you can also look into one of these:

http://www.4wheelparts.com/Performa...c=74&t_s=33&t_pt=5085&t_pl=4008&t_pn=SUP33002

Considering the fact that the dealer is going to charge $200+ per year to reprogram it for me, buying a unit to do it myself makes more sense. That Superlift Truspeed unit looks like just what I need and at pretty much the price for what the dealer would charge for a year's rotation, however their install guide lists the only compatible 3rd gen Explorers are the 2002-2003 Explorer Sport and Sport Trac. Is mine still compatible?

 

[LONO100]

just shoot 4wheelparts an email and ask them. they are pretty good at responding in a timely fashion. good luck and let us know what you go with.

 

[Teejay4490]

Those tires are barely bigger, theyre not really going to do much to affect anything, if anything at all.

 

[buckwill]

its not wheel size per se,, its wheel plus tire or total height times pi or total distance around,, the diff in your old tire from the new is total change

 

[Wills05xlt4x4]

its not wheel size per se,, its wheel plus tire or total height times pi or total distance around,, the diff in your old tire from the new is total change

Still I have to agree with only one size up it'll be fine..
Plenty including me run 265/75-16 over my oe 235/70-16..
Much larger change...

 

[Tvandyke]

Still I have to agree with only one size up it'll be fine..
Plenty including me run 265/75-16 over my oe 235/70-16..
Much larger change...

Running 265/75/16 tires does not cause the 4x4 auto to constantly kick on right? I have an 03 Ford Explorer and I’m just curious

 

[Mr. Alligator]

Running 265/75/16 tires does not cause the 4x4 auto to constantly kick on right? I have an 03 Ford Explorer and I’m just curious

Not if the tires are the same size and same tread wear.

Good luck.