Baystate Jeepers

Ok I am begging forgiveness ahead of time for this very newbie question but here goes.
About a month ago I put new tires on my Jeep. I replaced the stock tires she came with, with ToYo open country 265-70R16. My rims are 16" so I stayed with that. My question is this, are my tires 30" ( which is the number I get from one side of the tire to the other) or 32" because the radius is half the diameter (right?) ? Plus someone mentioned that my stock tires should have been 32". But when I measure my old I get 29" .
I am a bit confused and am hoping someone will take pity on me and help me understand, lol

Your tires have an overall diameter of 30.61". And no I did not use the website link below to figure that out. I have memorized all tires sizes ever made.

http://www.discounttire.com/dtcs/infoTireMath.dos

Also there should be a sticker somewhere that states what tire size the Jeep had when it left the factory. They are usually in the door jam or on the door itself.

So I guess if I am filling out an application that asks tire inches I can put 30.6 ok, will do. And thanks for that info! I can use that site. Not sure why it has to be so complicated, lol

Now,I wish I had that handy web site when I was shopping lol. I would have chosen the 75R

If you look at a manufacturer's website and find the tire model you're looking for you can usually find a "spec sheet" which will list all the tire sizes they offer for that model with detailed dimensions... This usually includes details about actual diameter and width measured in inches. I can be a bit of an eye chart to sort through, but it can help you tell exactly what you're getting.

JW

Now you tell me, lol

you hadn't asked! LOL!!!!

Your stock tires...
P225/75R16
P = Passenger car tire construction.
225 = width, in millimeters
75 = The aspect ratio. (75% of the tires width is the side wall height.)
R = Radial Construction
16 = Rim size.

Most tire companies mark the tire size based on their mold, not the product. So sizes do vary.
Very, very few companies mark the size of the tire based on the finished product.

Most JKs come equipped with a P255/75R17.
Rubicons and select models come with LT255/75R17.
LT = Light Truck Tire Construction
Both of the above tires are approximately 32" diameter.

Sahara models come with 18" rims. These are 18x6 rims. They're pretty narrow.
Sahara models are equipped with P255/70R18. LT tires are optional and some dealers will "upgrade" tires to an LT265/65R18 All Terrain tire.
These are also 32" diameter tires.

These JKs can usually fit a 33x10.50R16 (or R17) tire, but most of these tires in these sizes are actually the same size as stock. This is a flotation sized tire. It is much simpler to understand the dimensions of a tire marked in flotation size but the size discrepancy is usually larger than a P-Metric tire size.

33x12.50R16 (or 17 or 18) tires are not recommended on stock wheels. The tire itself is too wide for the rim, so the rides down the road on just the center and can't utilize all the tread, unless you air them down. By airing them down to make a better contact patch, the tire can become squirelly on the road, wear out the outer edge of the tread or worse - it can cause the tire to overheat and fail. (Ford Explorers and the Firestone tire recall - the door placards called for 26 psi in the front tires, too soften the ride and sell more explorers. The tires MINIMUM inflation marked on the sidewalls was 30 psi. 4 psi doesn't sound like a big deal, but it's more than 10% and resulted in several deaths from tire failure.)
Also, a 12.50" wide tire on stock wheels with a lift kit of any kind will cause the tires to contact the rear sway bar.
Wheel spacers or new wheels are required.

15" rims do not fit on JKs. No matter what anyone reads on any forum, it is a recipe for total disaster. They will only clear the brakes if the back space is reduced (the measurement from the wheel mounting surface to the inside of the rim) to around 3.5" or less. The disaster is a result of an increase in the scrub radius, placing leverage on the wrong parts of vital front end steering, drive axles and unit bearings. The operator ends up going through front end components quickly, as well as replacing the tires earlier than he or she should.

Blah, blah, blah.

JKs will tolerate a 2.5" lift, 34" tire before needing (and I mean needing) to be regeared.
JK Rubicons are not terrible on 35" tires because of their upgraded axle ratio, along with a 3.5" lift.

Any tire size change of more than one inch of advertised difference and the owner should get a hand held programmer to correct their speedo, abs, tpms, ASC and all the other initials. It's not JUST because the speedo is wrong, but because the JK is operated by a lot of computer signals. If the speedo is wrong, the JK will try to correct for what it thinks is correct. It gives poor automatic shifting, poor throttle response, sends too much fuel or air or not enough and generally just makes it drive like a bag of smashedassholes.

Kerri, if you were going to go buy tires again tomorrow with no other changes, I'd recommend LT255/85R16 Toyo MT and an AEV ProCal Module. Tall and skinny, aggressive tread, good road manners - works without a lift kit. They might require a little trimming of the splash shield under the front bumper.

Wow, looks like I should have found you guys before my purchase. I am fairly happy with my current tires but wanted taller, I did not know, nor did the salesperson tell me about the AEV to recalculate everything correctly.

Kerri wrote:Wow, looks like I should have found you guys before my purchase.

Which is why you should join Baystate sooner rather than later!

I have a few purchases to make first. I want to meet the requirements. I do not have a cb radio or a fire extinguisher. And my spare is stock and not likely to meet the requirements. I am working on the cb radio first, let me tell you, I never thought I would be buying one of those, lol. My younger self would be belly laughing at my current self.
Oh, and tow straps.

Kerri wrote:Oh, and tow straps.

Most will probably be recommending a "recovery strap" as a opposed to a tow strap initially. And NO metal hooks!

I can get that easy enough. I really want to do the off road thing with her. I have taken her to some light rocks and mud, light mountain terrain in Vermont just to get a feel for it. Loved every minute, my mileage dove to like 8MPG on the mountain trails lol

Thanks for starting this post. I learned a lot about tires right here.


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