Hey yall quick question. I've been wanting to get a PCM tune for a while but have been putting it off cause I'll be switching from the stock 265s (31" I think) to 305s (33" I think). Problem is I've got at least another 20k miles left on my 265s. I was just gonna suck it up and wait till the new tires but in researching here I read that the original PCM is tuned for 33" tires anyway so it wouldn't matter if I got the PCM now and switched tires later. Thoughts?

 

Adventures and Lux Off Roads came with 33s from the factory, their PCMs were set for 33s.

The rest came with 32" tires (265s) so their PCMs were set for 32s.

If you were going to do other mods (Intake, Exhaust, PP TB etc...) then do those first before the PCM Tune, otherwise..... go ahead and get your PCM done, your truck will think/show it is going a bit slower than it really is. Like 3-4 MPH on the Eways until you put on the new tires.


Personally, I would pull the 32s right now, they have no business being mounted on an H3. Sell those on CL for whatever you can get to offset your new purchase.

 

Thanks Doc! Couldnt have asked for a more succinct and reasonable response. Would the small increase in tire size sway your decision in choosing a set of replacement shocks? As many people are around here, I'm torn between the Bilstein 5100s and the Monroe Reflex series (95% highway, 5% very soft-occasionally bumpy sand).

 

go somewhere in between on the shocks. I do not like to run monroes on anything that I run off the pavement. Look at pro comps or other offroad shocks that are not as expensive as the Bilsteins.

 

Thanks sir!

 

That's backwards, if your computer thinks it has bigger tires than it does it'll think/read that you're going faster than you actually are, probably around 4 mph give or take at different speeds. If this is a great concern just use GPS on your phone from an app like Waze to monitor your speed.

I have 35s with the stock program and once I get to around 30 mph I am going about 5 mph faster than it reads, below 30 mph it's correct via my in car GPS unit, phone GPS, and those police "your speed is" radar signs they set up around cities and construction sites.

 

Did you get the point...... or no?

 

Weighing in on this, if you haven't gotten the shocks already...I got the Monroe shocks and found them to be softly valved. They are soft and let the truck move around too much. A base H3 has stiffer valving and I think the stock Adventure shocks are the best all around shock. The Bilsteins are a pretty stiff shock at the other end of the spectrum. I think Skeeter had some good advice for you there.