Necessary to regear for 33” tires on 3:45 ratio?

[donmontalvo]

So glad I found this thread. I have a JL with 3.45 stock gearing, and 245/75R17 that measure 31.5" at 36psi.

Was thinking of goingwith 33 or 35" tires, but then realized my garage opening height would clip the roof of the Jeep (rental apt).

We settled on 285/70R17 which is about 32.5", which is what I had on my previous Jeep (before I totaled it).

The first Jeep was a manual 3.6L, the new Jeep is an automatic 3.6L...will post findings once lift is installed next week.

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[01tj]

255/80/r17
33.3 inch Toyos

stock 3.45 gearing

Definitely feel the hit with the extra weight. But I would say a re-gear isn't absolutely necessary. I do tend to use the manual shift mode in my automatic that helps alleviate some of the shift points because the Auto tends to always want to go in the highest gear and bog out. Maybe when I get a little more coin I will upgrade to 4.56. But as for now I'm happy and it's doable

Have you had these off road? I had several different size tires on my old 4cly TJ but the 33/10.50 BFG MT/KOs were by far my favorite. It seemed like the 4cly had an easier time pushing the skinnies.


Anyone running these with the 6-speed manual?

 

[rsmit42]

So glad I found this thread. I have a JL with 3.45 stock gearing, and 245/75R17 that measure 31.5" at 36psi.

Was thinking of goingwith 33 or 35" tires, but then realized my garage opening height would clip the roof of the Jeep (rental apt).

We settled on 285/70R17 which is about 32.5", which is what I had on my previous Jeep (before I totaled it).

The first Jeep was a manual 3.6L, the new Jeep is an automatic 3.6L...will post findings once lift is installed next week.

 

[rsmit42]

Have you had any problems after installing the 285’s. Any shifting problems with your transmission?

 

[Uhdinator]

You need to add specifics when discussing this topic:
1. 2.0 or 3.6 engine
2, Auto or 6 speed
3. 4 door or 2 door (a Sahara 4 door Auto 3.6 is about 300lbs heavier than a 2.0 2 dr sport Auto, now add 4 people in the sahara and it will feel like a dog compared to a 2 door 2.0 Auto with 2 people) Now add cargo and heavier bumpers and winch. How much power loss you feel will depend on that as well.
4. Did you re-cal the speedo (effects shift point in auto, can effect ABS as well in auto and 6 spd)
5. Don't go by advertised tire size as it is given as unmounted unloaded height.
Re-cal for tire size requires measured height of mounted tire under load.
6. The 6 speed 1:1 gear is 4th gear, 8 speed 1:1 gear is 6th. 1st gear on the 6 spd is lower than the 8, but after that 2nd, 3rd, in the auto is lower than 2nd and 3rd in the manual and the auto has 5 gears closer together in ratio before 1:1 @ 6th making acceleration different than the manual.
7. The Auto will gradually adapt to your driving habits and adjust shift points to higher RPM's if you drive aggressively. Point being, this will cause the trans to not want to shift into 8th at times as you have trained it to not shift until higer RPM's are reached.
8. Regarding MPG change......dis regard your jeep readings if you haven't re cal'd the speedo as it is lying to you and your odometer will be off as well if you go a long time without a re-cal. MPG is significantly effected by speed of course.......youre driving a brick. Above 65 MPH the MPG drops significantly.

My 2 dr Sport Auto 2.0 has 305/65/17 tires at advertised height of 32.7 (measured height about 32") I had to use 31.75" as tire height in my flash cal to get the re cal to be within 1 mph of the speedo. Smart phone GPS app used to measure actual speed (with phone not plugged into USB as this can cause phone to read the jeep speed from the jeep not the app).

My 2 dr Auto 2.0 E torque will handle a little bigger 33's (295/70/17) just fine. A 4 Door 6spd will likely feel less peppy with the same. Most stuff I have found/read lean to the Auto handling bigger tires better than the 6 speed, likely due to more gears that are closer together. I re-cal'd the speedo and 8th gear works fine when not climbing hills.

 

[Chief20]

I’ve been running 17x9’s with a 4.75” backspace on 33’s 11.5 wide, no lift, without any issues at all. Tires are Nitto Ridge Grapplers. Would highly recommend.

Old pic:

I would however regear if going to 35’s and up. Just my personal opinion. I have M186/M220. 6Spd M/T

Note: my tires actually measure nearly 34”

Hi Morton, how are the nitto ridge grapplers doing you still in florida? I got a sport altitude jlu and looking to upgrade the 255/70r18 (32.1 h/t tires came stock) to 265/70r18 (32.6) for right now. Looked online and local shop got the best price so far 200 a pop including installment and all. Tires are 8 lbs more than stock at 45 lbs a tire.

 

[TrailTorque]

Hi Morton, how are the nitto ridge grapplers doing you still in florida? I got a sport altitude jlu and looking to upgrade the 255/70r18 (32.1 h/t tires came stock) to 265/70r18 (32.6) for right now. Looked online and local shop got the best price so far 200 a pop including installment and all. Tires are 8 lbs more than stock at 45 lbs a tire.

Hey buddy, yes I’m still in FL and I love them man. Still on the SAME set as that post haha 40k on them now and I don’t see an end in sight!

 

[Chief20]

Hey buddy, yes I’m still in FL and I love them man. Still on the SAME set as that post haha 40k on them now and I don’t see an end in sight!

Ok perfect thanks for reply and feedback. Take care, will be ordering and putting them on

 

[TrailTorque]

Ok perfect thanks for reply and feedback. Take care, will be ordering and putting them on

NP broski! Glad to help!

 

[Chief20]

NP broski! Glad to help!

Hey pal one more thing so i came across this and wanted to ask you , there are the 3 different sizes, does this mean they are different plys ? And if i get the standard 265/70r18 is the ply the same and since i drive its my dd , can i still take it off road even if the ply isnt e rated? Please let me know : (sending both for the 17 and 18 just so you can see )

 

[TrailTorque]

Hey pal one more thing so i came across this and wanted to ask you , there are the 3 different sizes, does this mean they are different plys ? And if i get the standard 265/70r18 is the ply the same and since i drive its my dd , can i still take it off road even if the ply isnt e rated? Please let me know : (sending both for the 17 and 18 just so you can see )

Let me take a look at my old invoice but I have the 17’s. I take mine off-road at least once a week without issue..

 

[TrailTorque]

Also to note I have a Sport with a Rubi suspension and .5” Teraflex hockey pucks..

 

[Chief20]

Let me take a look at my old invoice but I have the 17’s. I take mine off-road at least once a week without issue..

Okay that would be perfect thats what i plan on doing. I need to get rid of these dueler H/t’s. Thank you

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