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#676886 - 02/11/11 09:57 AM biggest tires you can fit
EricD Offline
Member

Registered: 05/10/11
Posts: 13
Loc: Metrowest, Taxachusetts
I ve done a search on this forum, google, and a few others. Now I'm here looking for all y'alls expertise! I have a 2011 Pro-4x. Can anyone tell me the biggest tire I can put on her WITHOUT having to change the gear ratios?
Actually, now that I mentioned it...has anyone changed their ratios? Why? Just for wheeling/ tires or does it help with gas mileage or some other reasons?

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#676887 - 02/11/11 12:07 PM Re: biggest tires you can fit [Re: EricD]
hugetanker Offline
Member

Registered: 15/05/11
Posts: 22
I know on 2nd gens that you can fit 33's or 285/75/16's with what they call the "melt mod". You don't need a lift or any trimming. Just a hair dryer. Here is a link to a "how to". Keep us informed on what you decide to do and post up some pics.


http://www.clubxterra.org/forums/showthread.php?t=6021

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#676895 - 03/11/11 08:42 AM Re: biggest tires you can fit [Re: EricD]
TJ Offline
Member
*****

Registered: 08/03/01
Posts: 7756
Loc: Lawrenceville, NJ, USA
Originally Posted By: EricD
I ve done a search on this forum, google, and a few others. Now I'm here looking for all y'alls expertise! I have a 2011 Pro-4x. Can anyone tell me the biggest tire I can put on her WITHOUT having to change the gear ratios?
Actually, now that I mentioned it...has anyone changed their ratios? Why? Just for wheeling/ tires or does it help with gas mileage or some other reasons?


You never HAVE TO change your gear ratios.

If you ever had a 10-speed bike, etc...you might remember that the PEDAL had gears and the rear WHEEL had gears on them.

If you were going up a steeper hill, you would shift to the lower (Numerical) gears, with 1st gear being for going really really slowly up a steep hill, while pedaling really fast.


That would mean you had lots of POWER to get up the hill, but you could not PEDAL fast enough to go as fast as you could go in 10th gear, etc.


If going on a flat area, once you got up to speed, you could shift UP to 10th gear, and go very FAST, while pedaling very SLOWLY.

THAT would mean you had very little POWER, but, you COULD pedal at a reasonable pace and go pretty fast.



Its the same for gearing on your truck.

For most engines, they make more power at higher RPM...so, if you NEED more power, you either don't upshift...so the RPM's rise as speed increases, or you downshift, to make the RPM's higher for the speed, or, change to lower gearing....so your RPM are ALWAYS higher, etc.

If you want more power, you change to lower gearing, either by shifting down, or, replacing the ratios in your drivetrain....and that means, for the same road speed, you are running at a higher RPM.


If you are able to get your head around all that....just imagine you swapped on larger tires, so it takes more torque to turn them (Its a longer lever arm from the hub to the ground...).

Now imagine if you'd need more rpm to GET that extra force, or, if the forces you have are enough to move the truck.


Obviously, the truck still can move...its just a little harder.


Essentially, if you go from say your stock 32" diameter tires, to 33" tires, such as going from 265/75/16's to 285/75/16's...

you'd take 32/33 = 0.97, and see that its a ~ 3% difference.

So, its ~ 3% harder to push the truck along.

That's sort of like adding ~ 125 lb or so your your cargo load, or having ~ a girlfriend sized passenger, etc.

If you were going to get a GF/unsuspecting victim, would you change how you drove, or, modify the vehicle to compensate for her weight?

If not, then getting 33" tires would not be a big deal.

If you would go to a mechanic before picking her up for the date/kidnapping, and have him modify the truck to compensate for the added load...then, sure, you'd do the same thing for the 33" tires.



laugh


If off roading, you typically need to go very slowly over rough terrain to avoid breakage...you CRAWL along.

If idle speed is too fast for where you wheel, IE: There are no more gears to down shift TO...you are in 1st gear, and low range on the transfer case, and STILL going too fast...or, you can idle along at a reasonable speed, but, at that RPM, you can't make enough POWER to climb the obstacles, etc...well, then you DO want lower gears.

If OFF road is the only place that this happens to you, you can JUST replace the LOW RANGE T-Case gears...so in 2wd high, etc...its the same as before...but, in LOW RANGE, you have almost double the RPMs for the same ground speed...or, you can idle along at HALF the speed, etc.


If the problem ON the road is due to that same chick you got being destined for burial in a piano case (Due to her excessive weight...), and/or you are running much larger tires than discussed plus armor/pulling a trailer through steep mountain passes, etc....

...Then you might change the DIFFERENTIAL gears to raise the RPM at any given speed...providing more power.

The DOWNSIDE to that is that you are ALWAYS at a higher RPM than you WOULD have been at.

So, when cruising along on the flat hwy...your mpg is generally lower, because its like you never upshifted to overdrive, etc.


Throw ALL the above together, and you have why some people re-gear (Not for 33's though...), and some don't.


laugh


Edited by TJ (03/11/11 08:57 AM)
_________________________
- TJ

2001 Xterra '03 VG33, SE 5 spd, 305/70/16's, Revolvers, UBSkidderz, Doubled AAL's, 3"SL/2"BL, winch/bumpers, skids, sliders, OBA, Snorkel, pine stripes....

Friends don't let friends drive stock.

http://www.gifsoup.com/view/501230/tj-tackling-crawlers-ridge-o.gif

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#676897 - 03/11/11 09:13 AM Re: biggest tires you can fit [Re: TJ]
EricD Offline
Member

Registered: 05/10/11
Posts: 13
Loc: Metrowest, Taxachusetts
Thanx TJ!
That makes sense. It sounds like an expense I dont really need right now then! But, one little issue....NO chicks over 110 lbs for me!!!! lol!

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#676898 - 03/11/11 10:17 AM Re: biggest tires you can fit [Re: EricD]
TJ Offline
Member
*****

Registered: 08/03/01
Posts: 7756
Loc: Lawrenceville, NJ, USA
Originally Posted By: EricD
Thanx TJ!
That makes sense. It sounds like an expense I dont really need right now then! But, one little issue....NO chicks over 110 lbs for me!!!! lol!



LOL

Hey, tall chicks wrap better.

laugh
_________________________
- TJ

2001 Xterra '03 VG33, SE 5 spd, 305/70/16's, Revolvers, UBSkidderz, Doubled AAL's, 3"SL/2"BL, winch/bumpers, skids, sliders, OBA, Snorkel, pine stripes....

Friends don't let friends drive stock.

http://www.gifsoup.com/view/501230/tj-tackling-crawlers-ridge-o.gif

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