Bigger tire question

jdeanrbl66

jdeanrbl66

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Joined
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Location
Ohio
Hi!… I am new to this forum and I am not schooled on tire upgrades and what not… my current vehicle is a 2014 jeep wrangler unlimited sport.. The rims I have on there now are 17 x 8 1/2… The tires that are currently on there are 255/75R17…on the box The rims came in it says ET = -18 which I looked up I believe means the offset is 4.25… I will not be going off-road with this vehicle at all I am just “theming“ it… that being said..my question is can I put 285/70 tires on those rims and not have to get a lift or put spacers… I understand I might have to trim or take off that piece of plastic that’s just under the fender because of possible rubbing on that… I have been looking at different forums and I’m not sure if I will have to do something with the gears… I hope I’m asking this all the right way.. because if I have to do a lift or put spacers in or mess with the gears I won’t do it was just hoping I can put the larger tire on there and be done with it… any info would be great thanks for replying in advance! I attached a photo of the outside of the box the rims came in also

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It looks as though you already have a lift of some sorts. You will have to recalibrate your speedometer and depending on what gears you have you might have to do a gear change.
 
I bought this Jeep in 2020 and all I have done is buy new rims and kept the tires because they were good.. The person who had it before had the stock rims and tires how can I tell if it’s been lifted?.. and how do I find out about the gears you were talking about?
 
OK thanks for the links I now found out that I have a 2 inch lift already on there and as far as the link to find out the gears I don’t necessarily know what to look for on that long list don’t know what verbiage to look for that being said if I already have a 2 inch lift couldn’t I technically put 285/70 on there?… with only having to adjust the speedometer and gears I would imagine they had to of done one of those possibly when they did the lift because it’s still had the stock tire and rim on there when I got it
 
It will tell you what gears were on your Jeep when it was built either 3.21, 3.73 or 4.10. One of those sizes will be on your build list.

If you have 3.21's and a automatic the Jeep won't be real happy with them but you'll be OK mostly on driving on flat roads without much hills.
 
It does say 3.21 rear axle ratio…is that it?.. also what all goes into changing the gears is that something you take to an auto shop and is it expensive also like I said I’m not doing any offloading just normal driving
 
jdeanrbl66 said:
It does say 3.21 rear axle ratio…is that it?.. also what all goes into changing the gears is that something you take to an auto shop and is it expensive also like I said I’m not doing any offloading just normal driving
Click to expand...

There was just a Member asking the other day about gear prices and it looks close to $2,000 for the gear change. If it has 3.21 then that's what you have.
 
OK if I do put those tires on and don’t do the gear change am I just looking at lower gas mileage and slightly sluggish going up hills?
 
jdeanrbl66 said:
OK if I do put those tires on and don’t do the gear change am I just looking at lower gas mileage and slightly sluggish going up hills?
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With the bigger tires you're going to get slightly lower gas mileage and it will feel ever so sluggish up hills. Get the Jscan app and a dongel. I used iCar Pro with Jscan. This helped recalibrate my speedometer and shift points which helped my Jeep feel more stock.
 
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JeepJeezy said:
With the bigger tires you're going to get slightly lower gas mileage and it will feel ever so sluggish up hills. Get the Jscan app and a dongel. I used iCar Pro with Jscan. This helped recalibrate my speedometer and shift points which helped my Jeep feel more stock
Click to expand...
Is that the app you’re talking about do I need the icar pro also?

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Here is the site I use to get a better idea of what a new tire size is going to mean. If you click around, there are a bunch of tools get quite a bit of information about tires and sizes.

tiresize.com

Tire Size Calculator

The best tire size calculator. Use our tire size calculator to find tire size specs and suggested tire sizes. Then check prices for all available tire sizes.
tiresize.com tiresize.com
 
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