Want to go bigger

Spic

Spic

TJ Enthusiast
Joined
Jun 14, 2018
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So like most I wouldn't mind going a little larger with my tyre, My 99 manual sport is all standard, altough I have ordered new 7" arches of the bay as one of mine is damaged/scuffed. Anyways I want to fit the biggest tyre without having to regear or basically change anything on the suspension, I don' mind chucking on some wheel spacer if need be though, Im under the impression my wheels are 15x7, Im also a little lost as far as sizes go, its the first time I've had anything to do with 4x4 tyres and every time I try and Google the info I'm looking for I'm only getting back info about 31's, 32's ect which i understand to be the height of the tyre, but never see anything about the width and rim size ?
Many thanks
Steve
 
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Hi, thanks for the reply, I've used the secound link but not sure how it works out my ratios ? All I know is the jeep currently has 225 75 15's, guessing I will have to grab the vin and find away of finding out with that
 
Hi, Rob, from what I researched my wheels are only 7" wide ? 31 x 10.50 whats that in normal car tyre sizes ? This is where I'm getting lost
 
Spic said:
Hi, Rob, from what I researched my wheels are only 7" wide ? 31 x 10.50 whats that in normal car tyre sizes ? This is where I'm getting lost
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You can run a 31x10.50 on a 7" wheel. If the tires rub on the control arms just add a washer or two behind the steering stop.
 
Rob5589 said:
You can run a 31x10.50 on a 7" wheel. If the tires rub on the control arms just add a washer or two behind the steering stop.
Click to expand...
No way will a 10.5 work with stock rim backspaceing. A wheel spacer could be used to fix that but a new rim is a better bet.

There are a huge number of things to figure out.

Gears (there's probably a metal tag on the diff cover between two bolts that tells you the ratio.)
If you have 307 gears 31s will make you hate life, particularly wide ones. 3.73 it depends on your transmission if the set up will work out.

Also how sagged are your springs? With the age of the jeep 31s may have fit fine when it was new, possibly not so much any more, hard to say.

If you plan to wheel it, then plan on the tires rubbing on the fender flairs when the suspension articulates.

31x10.5x15 is about 265/75/15

But LT tires can be bought in inches sometimes. Any tire shop should be able to figure this out for you. If not go somewhere else because apparently they don't know what they are doing.

—
There must have been a time
when we could have said no.
 
I have 33x10.50x15s on the stock steel 15x7 spokers. And I added 1 washer. The suspension is all stock, but the body has a AEV HighLine. I have no clearance issues. No lift. No spacers. And I cut the 6" AEV flares down to 4".



IMG_2223.jpg
 
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The real clearance issue with 33s on a stock suspension and 5.5" BS rims is the trailing edge of the front wheel opening. AEV cuts a big wedge out to clear the tire when turning, articulating. Anyone could do that easy even on a stock fender.

IMG_2201.jpg
 
Here is the formula for converting "metric" sizes to "inch" sizes - if that helps. But, using 265/75/15:
Diameter - 265x75x2/2550+15 = 30.6"
Width - 265/25.5 = 10.4"
 
Drizit said:
No way will a 10.5 work with stock rim backspaceing. A wheel spacer could be used to fix that but a new rim is better.
Click to expand...

Not true, you can run a 31x10.5 on a stock 15x7 rim. I did it for several months when I got my TJ. And the PO did it too for over 3,000 miles.

Spic said:
Hi, Rob, from what I researched my wheels are only 7" wide ? 31 x 10.50 whats that in normal car tyre sizes ? This is where I'm getting lost
Click to expand...
Use a Tire Converter tool like this one:

http://www.crawlpedia.com/tire_size_converter.htm

A 31x10.5r15 is equivalent to a 265x75r15

When would you have to regear? Well, as someone else said, we need to know what gears you have now? 3.07 or 3.73.

We also need to know what transmission you have? Auto or Manual? 6-speed or 5-speed? Overdrive?

If you don’t know these things, you can type in your VIN here and see the original factory build.

https://jeep.custhelp.com/app/jeep/eqlisting_detail/

More than likely if you have the dreaded 3.07’s, you’ll want to re-gear at some point.
 
Drizit said:
If you have 307 gears 31s will make you hate life
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yes, no. I did 33s, 3.07s for 11 years. I just never used 5th gear, overdrive. But there were no performance issues. Actually since I like to drive fast on forestry roads..... It was the best combination. A tall, 3.07 rear end gives a wide speed range in each gear. And in 4L, I could hit 60mph in 5th. That YJ drove like a Mustang, thanks to 3.07s and 33s.

When you give advice you need to qualify your response..... and we need to know what the OP wants to do. There is no wrong combination. There is only a wrong combination for you.... or me. Personally, after running 33s on my TJR for 9 years, I wish it had 3.73s instead of the Rubi 4.10s.
 
Thanks for the replys, it' appreciated, the jeep has a 5 speed manual box, as far as what I'm going to use it for, mainly road use, with about 20% light off roading, so dirt tracks, across sailsbury plain where the tanks train, and to be honest the last few times Ive driven there its been in discovery or freelander with road tyres, so its light off roadng really
I have tried the site to get the build sheet on my jeep but its saying it can find it so I will get underneath it after work and see if I can get the info I need off the casings
 
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OK so not having much luck, been under the jeep and the back diff has a tag but you can' read it or make it out at all as its rusted and there no tag at all on the front, I tryed the build sheet link again but it' only saying no information found...
Where can I go from here ?
 
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