Guys who went to 35's . . .

[JWSchmidt3]

Are you having any issues with, or does it seem your transmission shifts at much different intervals than from stock?? I had an Adv. H3, and I am currently driving a 2007 dealer loaner while my lifted H3 is at the dealer, and my suspician is confirmed. One of the issues I sent the H3 in for is the tranny shifting. It always wants to shift down to low gear way too early. Is this because of the 35's?? Is there any way to properly calibrate the bigger tires?? My truck drives like a turd compared to thos '07. BTW, I also have a CAI and exhaust installed. Any help appreciated, as the dealership has yet to give me any real hope.
:beerchug:

[HummBebe]

I think your only option at this time is to pay for it to be professionaly tuned.

GM has no computer re-program as of yet.

[meyergsr]

Your going to have to get your engine computer recalibrated for the taller tires the dealer wont do it. Go to the aftermarket like PCM for less. http://www.geocities.com/pcmforless/index.html

[JWSchmidt3]

Here's another issue, I bought the truck new from the dealer with this package installed (they call it the Xtreme Comp Pro package). The sales guy specifically said, "Oh yea, it's all been re-tuned for the bigger tires, intake and exhaust. They use the Tech-II". My extensive modding with Corvettes told me he was probably full of it, but I'm now holding them to it. I'm just curious if anyone else had such a drastic impact when they changed to 35's, or if I have another issue.

[CrisB]

You bought that H3 like that? The dealership probably did that themselves, somebody there thinks he knows what he's doing. I would definitely hold them to it, they built it.

[HummBebe]

Here's another issue, I bought the truck new from the dealer with this package installed (they call it the Xtreme Comp Pro package). The sales guy specifically said, "Oh yea, it's all been re-tuned for the bigger tires, intake and exhaust. They use the Tech-II". My extensive modding with Corvettes told me he was probably full of it, but I'm now holding them to it. I'm just curious if anyone else had such a drastic impact when they changed to 35's, or if I have another issue.

That is an outright lie. There is no Tech II program for tire increase to 35". Only from 32" to 33".

[JWSchmidt3]

You bought that H3 like that? The dealership probably did that themselves, somebody there thinks he knows what he's doing. I would definitely hold them to it, they built it.

Yes, but they contracted an offroad shop to do the package. The dealership is pretty reputable. I'll hold them to it, but the fact remains the PCM can not be properly calibrated for the bigger tires, and I'm wondering what other guys who have gone to 35's have done.

[JWSchmidt3]

That is an outright lie. There is no Tech II program for tire increase to 35". Only from 32" to 33".

That's what I thought when I bought it, but was only 99% sure. I won't call someone out unless I'm 100%. Tomorrow I pick up the truck, and meet with the Hummer GM.

[HummBebe]

I'm wondering what other guys who have gone to 35's have done.

Wheel the hell out of it :jump:

[K9sH3]

JW,
I would hold them to it also, they lied (fraud) to sell you a H3. If you have that in writing you may have a new 3 coming if this one turns out to be a POS. In the mean time, I would do as Hummbebe said "Wheel the hell out of it" they (dealer) customized and gave it that name.

:beerchug:

[Steve - SanJose]

No amount of so called tuning combined with aftermarket intake and exhaust systems will counteract the hit to acceleration caused by the larger diameter 35" tires. Your gearing is now substantially taller than the stock H3 w/32's or 33's.

[JWSchmidt3]

No amount of so called tuning combined with aftermarket intake and exhaust systems will counteract the hit to acceleration caused by the larger diameter 35" tires. Your gearing is now substantially taller than the stock H3 w/32's or 33's.

So, would a gear change help??

[Steve - SanJose]

So, would a gear change help??

Gearing change would certainly help. But others on this forum have researched that and can talk feasability.

[HummBebe]

No amount of so called tuning combined with aftermarket intake and exhaust systems will counteract the hit to acceleration caused by the larger diameter 35" tires. Your gearing is now substantially taller than the stock H3 w/32's or 33's.


Using a calculator would show that it reduces you to about 4:29's. Still better ratio than on an H2 :giggling:

[BACKNBLACK]

The Hummer H3 has "Adaptive" shift learning. Even going from 32" to 33" no computer "reprogram" is necessary. I have 35" BFG MT and mine shifted funny for about 3 days and then bang "Adapted" Talk to your H3 Mechanic he should be able to verify this. Hummer engineering has also commented on this in a few earlier articles during the "promotional phase of the H3" Hope this helps.

BTW here are the stats for the 35" Change from the 33'S"

http://www.hummercor.com/images/SPONSORS/TIRE.JPG

[BACKNBLACK]

BTW even with a 2 1/2 Turn of the TBAR I still rub against the plastic and A arm at full crank. Nothing to get nerveous about but just be aware that if you like a "RUB FREE" Hummer than 35'S" are not for you :-)

[JWSchmidt3]

BTW even with a 2 1/2 Turn of the TBAR I still rub against the plastic and A arm at full crank. Nothing to get nerveous about but just be aware that if you like a "RUB FREE" Hummer than 35'S" are not for you :-)

I already have 35's, along with a 4" lift. My issue is with the transmission and how it shifts. See my sig and original post.
:beerchug:

[BACKNBLACK]

I already have 35's, along with a 4" lift. My issue is with the transmission and how it shifts. See my sig and original post.
:beerchug:

:giggling: OOPS :-)

In that case....... is it possible the lift has caused your issue. In my Hummerclub that I manage none of my members that went to 35's have this issue longer than a few days??? The only difference is the lift???

[jdrew]

Wheel the hell out of it :jump:


+10 points for an excellent post! :) :beerchug:

[lotus4s]

I already have 35's, along with a 4" lift. My issue is with the transmission and how it shifts. See my sig and original post.
:beerchug:

As someone else suggested, contact PCM for less. They can adjust the shift tables....

[JWSchmidt3]

As someone else suggested, contact PCM for less. They can adjust the shift tables....

Looks like I'll be doing the PCM for Less. The dealership finally stepped up, and agreed to properly set the PCM with my recommendation of the PCM for Less. I take it in next week, and pick up the loaner until it's done. Will report back the difference after I get it back.

[wpage]

Do the math on a long page. Take your time with whatever you decide. Count to ten. Take a deep breath. Then tell them all your going with the competition!

[JWSchmidt3]

Do the math on a long page. Take your time with whatever you decide. Count to ten. Take a deep breath. Then tell them all your going with the competition!

:confused: :confused: :confused:

[Steve - SanJose]

I doubt the PCM is the solution anyway.

[JWSchmidt3]

I doubt the PCM is the solution anyway.

Then what is?? :confused:

[Steve - SanJose]

Based on the way GM thoroughly engineered the H3, 32" or 33" inch tires are optimal, since a gearing change is not readily available.

[JWSchmidt3]

I doubt the PCM is the solution anyway.

You would be incorrect. Just got back the H3 over the weekend, and it now drives great.

I'll do another post about it when I get a chance.

:beerchug:

[Steve - SanJose]

You would be incorrect. Just got back the H3 over the weekend, and it now drives great.

I'll do another post about it when I get a chance.

:beerchug:

Good to hear it's downshifting less, which means the acceleration is that much slower than stock as engine lugs in higher gears.

[marin8703]

question for you smart people. I am in the final stage of getting 35s but have one final question. I noticed most of you that have 35s have the adventure package which has the 4:1 transfer case. I dont have that, i have the basic.

I dont know what the gearing is in the base transfer case or how it would effect anything so this is my question. Would I, with the regular transfer case, notice any difference in perforemance (decrease due to the larger tires) more than you guys have or just the same?

Thanks,
Marin

[JWSchmidt3]

this is my question. Would I, with the regular transfer case, notice any difference in perforemance (decrease due to the larger tires) more than you guys have or just the same?

Thanks,
Marin

Probably the same, but you're starting with less (in gearing) to begin with. IMHO

[marin8703]

so what does that really mean, that i am starting with less gearing? In the t-case are the hi and low gears different from the base to the adventure or only the low? Thanks!

[Sewie]

so what does that really mean, that i am starting with less gearing? In the t-case are the hi and low gears different from the base to the adventure or only the low? Thanks!

Only the low range gear ratio is different. The only gearing difference for day-to-day driving would be between a manual and an auto.

[marin8703]

Only the low range gear ratio is different. The only gearing difference for day-to-day driving would be between a manual and an auto.

does anyone know if the pcmforless thing would calibrate the truck for 35s. The reason that i wopuld like this is because of my nav, it uses the VSS, is teh differnce between 33s and 35s gona throw it off. the nav is an aftermarket pioneer avic-z1.

i know this can be done my purchaseing a speed pulse generator from pioneer but its around 250, and it would be used only for the nav. are there any other options?

thanks.

[Desert Dan]

I Agree with Steve in San Jose

"Based on the way GM thoroughly engineered the H3, 32" or 33" inch tires are optimal, since a gearing change is not readily available."

Since we have an I-5, gearing is the only way to compensate for 35" tires. Off road in 4:1 low you might not notice it too much but on the highway?

35" tires are alot bigger than 33". If you change axle gears to 4:88 or lower the teeth on the gears get thinner (smaller) which are more likely to break and with bigger tires you are putting more leverage on half shafts, u-joints and front diffs.

Without changing anything and going to 35" tires your gas mileage will go down and acceleration will suffer. No ifs ands or buts!

[Sewie]

Without changing anything and going to 35" tires your gas mileage will go down and acceleration will suffer. No ifs ands or buts!

That is true, but it is not as drastic as some make it out to be.

[Steve - SanJose]

I would think the hit to acceleration via the 35's would be significant, but not the gas mileage difference.

[Jeff G]

Are you having any issues with, or does it seem your transmission shifts at much different intervals than from stock?? I had an Adv. H3, and I am currently driving a 2007 dealer loaner while my lifted H3 is at the dealer, and my suspician is confirmed. One of the issues I sent the H3 in for is the tranny shifting. It always wants to shift down to low gear way too early. Is this because of the 35's?? Is there any way to properly calibrate the bigger tires?? My truck drives like a turd compared to thos '07. BTW, I also have a CAI and exhaust installed. Any help appreciated, as the dealership has yet to give me any real hope.
:beerchug:

I've had mine installed for less than 24 hours and I would highly recommend the PCM for less tune. Totally different beast with the 35's.:beerchug:

[marin8703]

another quick question. The about 7% difference in the speedo between the 32 inch stock tire and the 35 inch toyos, is that a linear diffrence or exponential? By that I mean if your speedo shows 65, then you are actually going 70, is the same true if it shows 15 the actual is 20 mph, or would it be different?

Also do you think that this difference (speedo 7% slower tahn actual) is enough to throw off an aftermarket nav (pioneer avic z1) which uses the speed pulse in doing its calculations?

also i didnt understand if the pcmfor less calibration of the pcm can calibrate the speedo for the 35s, can someone clarify that? I know they ask what tire you are ising but do they actually configure teh speedo?

thanks

[JWSchmidt3]

also i didnt understand if the pcmfor less calibration of the pcm can calibrate the speedo for the 35s, can someone clarify that? I know they ask what tire you are ising but do they actually configure teh speedo?

thanks

Yes, they fix the speedo with their tune.

[HUMMJAY]

JWS- you've had the new pcm for a couple of months now,,, how's it working?? I've had 35's on my truck for about 9months and would love to get my milage and proformance back,,,, I'm on the verge of going back to 33's

[NEOCON1]

Wheel the hell out of it :jump:


:beerchug: :giggling: :giggling: :giggling:

[westhillsat]

JWS- you've had the new pcm for a couple of months now,,, how's it working?? I've had 35's on my truck for about 9months and would love to get my milage and proformance back,,,, I'm on the verge of going back to 33's

My 75 cents worth.

I love the pcm change along with my dual exhaust from Jason
I got the Billy Boat exhaust

http://www.somo.com/

Average 12 - 13 mpg with the 35's, but have no acceleration issues now
and shifts great.

[Idaho-Hummer]

I love the pcm change along with my dual exhaust from Jason
I got the Billy Boat exhaust



Weshillsat

what does the billy boat exhaust sound like. is it like the stock exhaust ?

[JWSchmidt3]

JWS- you've had the new pcm for a couple of months now,,, how's it working?? I've had 35's on my truck for about 9months and would love to get my milage and proformance back,,,, I'm on the verge of going back to 33's

Works great. Couldn't be happier.

:beerchug: