Moto826
New Member
as long as they're 6x139.7 you'll be fine. I can guarantee you that they'll fit. almost every 6 lug chevy is a 6x139.7 bolt pattern!
Verifying that these rims fit & thoughts on looks
- Thread starter mars2878
- Start date
stutaeng
Well-Known Member
I believe my truck's OEM tires are 225/75/16 IIRC. Isn't that what your door tag shows @mars2878 ?
That would make the speedometer more off? Although you said you are getting that recalibrated. Your overall gear final ratio will also be affected. You have 3.42 gears I'm guessing?
That would make the speedometer more off? Although you said you are getting that recalibrated. Your overall gear final ratio will also be affected. You have 3.42 gears I'm guessing?
Marky Dissod
Well-Known Member
Those would be the most likely. Less likely but still possible is 265/70R17 for Z71.
My eyesight sees clearance problems and what is the offset? I could be wrong but with the, unknown as of yet, clearance after bolted to hub, unknown offset-between 18mm and 35mm-what? and complete difference in the tire sizes, I just see problems. But I am 73 and old. Who knows?
AuroraGirl
Well-Known Member
You also need to change the tire size in the EBCM which is the ABS system
This is critical for safety
stutaeng
Well-Known Member
Interesante.
I'd never heard of this. I'm pretty sure the ABS works just fine on my GMT800s that's I've changed the axle ratio and/or tire size. Speedometers are on point as well...
Marky Dissod
Well-Known Member
(I'm ALL for being corrected, but for the rest of this post it's gonna seem like I'm not, even though I am ...)
Huh? The ABS system cannot tell if the axle or tire size has changed, unless they have stopped matching each other.
ABS / Traction Control & speedometer actually operate independently of each other, despite sharing inputs.
All it cares about is that all four tone rings' speeds pretty much match (since we have 4Channel ABS).
If one or two of these rings is slower than the others by too much, ABS activates.
So long as the tire diameters/circumferences are (very (close) enough), the ABS system will work.
I.E.: the difference between 265/65R18, 285/65R17, 265/70R17, & 265/75R16 is not big enough to matter
(wheel size does not matter, only tire size matters to the ABS / Traction Control & the Speedometer),
so even if you were crazy enough to wear all four of the above on your vehicle,
the ABS / Traction Control & speedo would not notice the difference.
HOWEVER,
If you change the tire size by more than 2% taller or shorter than GM OE, your speedometer will be noticeably off.
If the new tires are taller, get the speedo corrected ASAP; a speedo that reads slower than real is potentially dangerous.
(OK, now, someone with better tech understanding, please feel free to learn me sumphen.)
AuroraGirl
Well-Known Member
the difference forr the abs system is because theDIAMETER and THE WIDTH because the module is the same as the lowly half tons through the 1 tons (I think)
Also consider the ABS only works over 4mph when the truck can accurately determine wheel speed, under 4 it simply cannot, and under 8 its not accurate enough for its liking, and the size diameter difference of any kind may interupt the speed of which it applies or when it stops, meaning it may not start ABS above the speed its accurate which means more potential to lose control of steering at low speed but sliding events, or it may not cut off at the right speed and you may end up reatr ending someone when you brake while barely moving and the module is assuming its accurate values and youre wheels are just locked up when its trying to stop
Also consider the ABS only works over 4mph when the truck can accurately determine wheel speed, under 4 it simply cannot, and under 8 its not accurate enough for its liking, and the size diameter difference of any kind may interupt the speed of which it applies or when it stops, meaning it may not start ABS above the speed its accurate which means more potential to lose control of steering at low speed but sliding events, or it may not cut off at the right speed and you may end up reatr ending someone when you brake while barely moving and the module is assuming its accurate values and youre wheels are just locked up when its trying to stop
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This PI was superseded to update model years. Please discard PIT3271C. The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI. [H3]Condition/Concern:[/H3] Changing of tire size on midsize and full size trucks and utilities. [H3]Recommendation/Instructions:[/H3] When attempting to change tire size, it is important to understand what tire size the customer is interested in installing. General Motors will ONLY support a tire calibration for tires that have been sized, tested and designed for the vehicle in question and its applications. DO NOT use the information offered in the ABS module (tire size selection) as a guide to see what tires are applicable to the vehicle in question. Keep in mind, changing the tire size in the ABS module will only affect ABS wheel speed sensor calibration that are direct inputs to the ABS module. It will not correct or calibrate the speedometer's accuracy, and will not change the calibration of the ABS rear speed sensor value on vehicles that obtain rear wheel speed data from the ECM/PCM/VCM via the VSS. [H4]Example.[/H4] 2004 Chevrolet Colorado LS with 235/75/R15 tires. The customer would like to install P265/75/R15 tires. Although ABS module shows this tire can be programmed, the 265/75/R15 will only fit under a Colorado with the Z71 suspension. This suspension will offer acceptable wheel clearance. Therefore, a calibration will not be offered for this application. [H4]Example.[/H4] A second example would be bulletin 03-03-10-006a, which offers 20" wheels and tires for the full size pick up trucks. A calibration has been developed for this specific application in response to popular demand from our customers. Accessories released an approved tire wheel combination that has been tested and validated by GM Engineering for a specific application. The only way to confirm that a calibration is available would be to visit YOUR sales department. Using the sales order guide, the following combinations of items must be available for the vehicle in question... If you can build a vehicle, using the sales guide, using the same model year, body style, engine size, transmission type, axle type and suspension type, any tire offered for that combination will be offered a calibration. If your sales guide does not cover the model year vehicle that is in question, please contact Techline Customer Support at 1-800-828-6860. Please do not call Technical Assistance Center for these concerns. Once the tire application has been confirmed per the sales guide, contact Techline at 800-828-6860 for a VCI Number. Please note, there may be a cost to the customer for this service. This is not a feature that is covered under the manufactures warranty. Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. |
AuroraGirl
Well-Known Member
speedometer being accurate is PCM calibration
The EBCM
The top part is the EBCM, the thing is called the EBTCM if you have traction control JL4 (i think is the RPO)
The brake lines go into the BPMV or brake pressure modulator valve which is in the middle here above that contains the motor and valves for ABS and rear proproportioning
The EBCM
The top part is the EBCM, the thing is called the EBTCM if you have traction control JL4 (i think is the RPO)
The brake lines go into the BPMV or brake pressure modulator valve which is in the middle here above that contains the motor and valves for ABS and rear proproportioning
stutaeng
Well-Known Member
Oh, ok. Yeah, I also replaced the EBCM on my truck a few years ago. I didn't get it reprogrammed tho. I just deleted the ABS/Brake codes and they didn't come back on. Been driving her all over the place now.
Will the dealership even try to do this programing if this document says this: "General Motors will ONLY support a tire calibration for tires that have been sized, tested and designed for the vehicle in question and its applications."?
Will the dealership even try to do this programing if this document says this: "General Motors will ONLY support a tire calibration for tires that have been sized, tested and designed for the vehicle in question and its applications."?
AuroraGirl
Well-Known Member
hub opening diameter, and older trucks
how about those? I would assume the hub diameter has to be larger on newer 6 lugs
AuroraGirl
Well-Known Member
you just need a tech 2. my mk808 can do it as well, autel scanner. So anyone with a mid-high range tool should be able to change it. it gives you a list of tire sizes. the list actually distinctly splits between the load range D tires on duallys and load range E on trucks without dually (1 ton) so thats why i think its important for its calibrations to have those, because the sam diameter and width shouldnt need a different selection. but the amount of flex, loads expected (possibly for DRP use?) etc will be different
So i measured the front & rear wheelwell openings at the mid-height of the hub, they are 35in across. So fitting a 33in in the opening shouldn't be an issue as previously concerned by someone?
Finally got a rear mounted.
Plenty of clearance all around.
This is with an empty bed.
I should be good enough to 2k lbs in the bed w/o touching the tire at stock 26yr old height?
Finally got a rear mounted.
Plenty of clearance all around.
This is with an empty bed.
I should be good enough to 2k lbs in the bed w/o touching the tire at stock 26yr old height?
stutaeng
Well-Known Member
Great news!
You can measure the distance between the top of the rubber and the wheel well, then compare that to the distance between the jounce stop and the axle pad. Probably should be fine. I think the payload on these is rated for around 1500-1600lbs?
But I once loaded my truck with a full yard of wet sand, which was like 2600 lbs. Oooops! LOL
You can measure the distance between the top of the rubber and the wheel well, then compare that to the distance between the jounce stop and the axle pad. Probably should be fine. I think the payload on these is rated for around 1500-1600lbs?
But I once loaded my truck with a full yard of wet sand, which was like 2600 lbs. Oooops! LOL
Here's the front. On its own weight. I still gotta turn the wheel to see if it catches anything?
Yeah, I know, wrong lugnuts. I'll get the correct ones once I know for a fact that there isn't any issues with fitment.
Yeah, I know, wrong lugnuts. I'll get the correct ones once I know for a fact that there isn't any issues with fitment.
stutaeng
Well-Known Member
Looks like you have a lot of room...Yeah, I have those standard lug nuts on my wheels too. SMH.
Maybe try to find a ramp or steep driveway where you can turn the wheel while flexing the suspension just to make sure you don't rubbing?
Maybe try to find a ramp or steep driveway where you can turn the wheel while flexing the suspension just to make sure you don't rubbing?
Full lock to the left.
Plenty of room at the rear.
Barely any room at the front.
There is some flexibility in the liner, so maybe making something to force the opening bigger?
I'll drive on my neighboring crappy road 1st, then I'll look for any signs of touching on the liner.
Plenty of room at the rear.
Barely any room at the front.
There is some flexibility in the liner, so maybe making something to force the opening bigger?
I'll drive on my neighboring crappy road 1st, then I'll look for any signs of touching on the liner.
stutaeng
Well-Known Member
Close enough to kiss! 
Ya, those rear jounce stops are like bad girlfriends: they hang with you so long, then don't even say goodbye when they disappear...SMH
Ya, those rear jounce stops are like bad girlfriends: they hang with you so long, then don't even say goodbye when they disappear...SMH
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