Jump to content

Increase 31.5" tire to 33" diameter tire

GMSEVEN

By GMSEVEN
in Modifications, Wheels & Tires

Recommended Posts

GMSEVEN Enthusiast

GMSEVEN

Posted
Posted

 I have a 2019 T1XX Silverado 1500 Z71 LT with 18" wheels and 265/65/18 stock goodyears with 31.5" diameter.  I want to increase to a 275/70/18 or maybe a wider 33" or even 34" diameter tire.   The RST's with 20" wheels come standard with a 275/60/20 Tire which is a 33" diameter...

So my question: is increasing from 31.5" to 33" diameter tires merit a rear end gear change or other ECU programming to accommodate the new diameter?   We all know that increasing the tire diameter changes the final gear ratio, but is it significant enough that would require any adjustments?   I would doubt that an LT 8-speed and 3.23 rear gear and RST 8-speed and  3.23 rear gear would have different components internally even though the tire diameters are different by 1.5".

Any comments would be appreciated,, probably nothing to stress about but my perfectionist mind likes to dwell on small details, and don't want to experience any acceleration changes, fuel economy decline or speedometer misreadings.

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

Changing the calibration isn't a 100% must do thing. It would only be off by about 3mph when going 70mph down the freeway.

 

You have the option to see if a dealership can program the calibration for the 33in size tires that would be standard on the different trims trucks.

 

I don't think you'd want to spend $1,900+ to do the tuning changes yourself with HP Tuners because that is the only aftermarket tuner on the market for those trucks.

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • C/K Man
      Silverado 4500-5500-6500 are they still being produced? Would have sold better as GMCs as well

      By C/K Man · Posted

      There was talk over the last couple of years that the contract to build these trucks between GM and International would not be renewed.  International moved production of all their other trucks besides the companion CV model out of the Springfield plant some time ago when they opened their San Antonio plant.  That left Springfield only building the Silverado Medium Duty, International CV Series, and some Express/Savanna long wheelbase cutaways.  International also put the plant up for sale some time ago.  This all answered my earlier question as to why GM and International did nothing with these trucks since they were introduced, as they had basically become a market 'placeholder' with a finite life.    The Silverado Medium Duty/International CV trucks were interesting combination of a GM powertrain, electrical system, and K2XX Silverado cab with an International chassis that was supposedly designed for a step-van type vehicle they never produced.  They were manufactured in International's Springfield plant along with the IH MV series initially.  When first introduced, there was much talk that the Silverado Medium Duty/CV would eventually get a gasoline engine option along with other upgrades and GM and IH would work on a class 6/7 joint venture truck.  This was before VW bought Navistar out, after that happened no more was said.  Draw your own conclusions...   About the time talk started that the GM/IH joint venture was not going to be renewed, rumors started that GM would develop a new line of medium duty trucks themselves.  The story is the new trucks will be part of the next generation HD's due in 2028, and will still feature a 'straight rail' chassis design that the current medium duty has.  GM views this as a desirable feature that differentiates their truck from the competition.  A gasoline engine option is also expected.  As the current Silverado Medium Duty remains in production until September 2026 and there is still a lot of inventory available do not expect any official word for some time.   I believe GM remains committed to their successful partnership with Isuzu, and all the LCF models will still be available from Chevy Commercial dealers.  Isuzu is on the cusp of opening a new large plant in South Carolina and there is also speculation that this may result in new product for both Isuzu and Chevy Commercial dealers.                  
    • davester
      push to talk button

      By davester · Posted

      drive the truck back to the dealer and complain that the button works.
    • davester
      push to talk button

      By davester · Posted

      drive the truck back to the dealer and complain that the button works.
    • nfisherman
      Software Update

      By nfisherman · Posted

      I have a 2026 2500 HD Ultimate. My phone app says there’s a software update available. It’s something about improved battery management and something to do with the running boards. I follow the instructions for the update but the “Check for Updates” option is greyed out in my settings menu. Has anyone else seen this? How did you resolve it? The help message just says “see your dealer” if the download doesn’t work. I’m just trying to save a trip. 
    • newdude
      Exhaust Question

      By newdude · Posted

      Fuel mileage?  That's all how you use your right foot.  Exhaust will give you sound.   Stock exhaust 5.3 is 2.75" diameter piping.     If the truck is nice and worth putting some $$ into it, I'd go for a Corsa catback.  I had one on my 2019 old body 5.3 and it was just perfect.  Zero drone, just driving around and cruising on the highway you'd think it was stock, but when you opened it up it was like a Camaro with the factory dual mode.  Corsa bumps their catback to 3in diameter.  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...