Cooper AT3 XLT

Good point. I'm sticking with the stock 18x8 wheels. The picture taken above shows ~1.25" LESS in diameter than the advertised number that Cooper has on the site. Crazy

 

Leaving this here from Tire Rack... Wheel wide has little impact on the overall diameter; however it will impact the tire face and the working width of the tire (see below)

https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=198


Rim Width Range
Because tires have flexible sidewalls, a single tire size will fit on a variety of rim widths. A tire's rim width range identifies the narrowest to the widest rim widths upon which the tire is designed to be mounted during its tens-of-thousands of miles and years of service.

The width of the rim will influence the width of the tire. A tire mounted on a narrow rim would be "narrower" than if the same size tire was mounted on a wide rim.

Note: Because the overall diameter of a steel-belted radial is essentially determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width.

The industry rule of thumb is that for every 1/2" change in rim width, the tire's section width will correspondingly change by approximately 2/10".

 

That's exactly what I was thinking. Rim width has very little to do with the final diameter. I'm now convinced that the 295/70/18 is what I want because of the "downsizing" that happens. This tire is NOT 34.25" in diameter; it's actually 33". Thanks for the feedback!!

 

I wonder why the website shows 34.25” on a 8.5” rim then? Maybe they take measurements at max pressure? 80psi?

 

33.75

275.65.18/295.70.18

 

@SprinterAE86 what size is that?

 

295.70.18

 

Too big for 18×9 +12

 

Love the comparison against the other tire. Also, really nice looking truck.

I went from 33/12.50/18 to the 295/70/18 size and I'll be honest was a little scared of them fitting.

 

Some rubbing, I need to do some more mods. Or get a different wheel with more positive offset.

 

Cooper Tire Discoverer AT3 XTL 295.70.18 18x9 +12 Bilstein 5100 bottom setting Tuff Country 2" Level Kit.

 

SprinterAE86: The first 2 pictures are showing an unmounted Cooper AT3 XLT in a 295.70.18? And it stands 33.75" tall?

 

Yes, that is correct. I'll measure it on the truck with air later.

 

Installed them last night.

 

Nice looking!

 

What mpg are you guys getting after going up to 295.70.18, 285.75.18 and 275.70.18?

I drive 25k a year and I think I can not justify the mileage cost of the 295.70.18. Before I purchase a lighter wheel with +25 and narrower tires and drop the suspension 1" I want to hear from you guys.

With the 3/1 lift with 275.65.18 I'm getting 16 on highway.
Now with 295..70.18, raised the truck 1"+.

My wheels is 32lbs, +12 wanting to get CS10 27 lbs +25. So I can lessen the weight and tuck it in a bit for clearance purposes and aerodynamics.

Thoughts?

@phogallen
@The_Bob88
@duece292
@Zero One Actual
@Tzvia

 

So my 295.70.18 Cooper AT3 XLT's arrived at the tire shop yesterday and I couldn't stop myself from going by and measuring the unmounted tire. I got the same dimension SprinterAE86 got which is 33.75". That's perfectly acceptable and can't wait to have them mounted up on Friday. I'm just wondering how vhstejskal measured his in post #387 at 33" tall???? Thanks for all the pictures fellas

 

Keep in mind my measurements were mounted tires; so with the weight of the truck and my current pressure the 3/4” is probably going to account for the difference.

 

I will have to get back to you on that. Just got them on and I haven’t filled up my tank yet

 

Am I missing something? What's the reason behind measuring an unmounted tire?

 

I think you're doing pretty well at 16 mpg with that setup. I'm leveled, so about 1.75" in the front and stock height in the rear, stock TRD wheels and 275/70/18 AT3 XLT's and right now I'm averaging 14.8 to 15.2. But... it's been cold (single digit cold) and snowy, so I've used my 4wd and that doesn't help my mileage.
I don't know how much you'd gain with changing wheels. You're lessening the wheel weight by 5 lbs but even going to a 275/70 you're still roughly 16lbs heavier than the P275/65's. Adding that extra 11ish pounds will have some effect. Again, at 16 I think you're doing pretty well if you're at 3/2 with 295's.

 

I completely agree. It just blows my mind that the manufacturer says a 295.70.18 has a 34.25" diameter, the unmounted tire is then measured at 33.75" and once it's mounted and under the normal weight of the truck it ends up more like 33" tall. Just sayin....

 

Just another data point. The manufacturer says the tire is 34.25" but once it's installed and under the weight of the truck it ends up closer to 33" in diameter. That's a big difference and factors into my final decision on tire size.

 

To add to @vhstejskal Vic's explanation of tire width... overall tire diameter is achieved by mounting the tire to a prescribed wheel, usually 8" or 8.5", airing up, allowing it to sit for 24 hours and then inflating to the max cold pressure and then measuring the overall diameter. But not mounted on the vehicle. That's why none of us will ever be at the measurements given by the tire manufacturers.

 

Keep in mind that your MPG calculations will not be accurate anymore. The circumference of your tire is different, so for each rotation of the tire you are going a little further than what your odometer is registering. In my case I went from 275/55/20 to 275/65/20, which is a 100"± circumference to 107"± circumference, or roughly 7% more. So, to calculate your MPG you can add 7% to the distance when calculating. That helps to soften the blow a little!. In my case I went down from 16 MPG avg to 13 MPG avg when I added the tires and lift (from the trucks computer and from hand calculating using the odometer = about the same answers). The reduced MPG is probably because of both the heavier tires and the lift aerodynamics.
In reality my MPG is about 7% better than calculated, so closer to 14 MPG.

 

@duece292 Greg, I was getting 16+ with the 275.16.18. I am now getting 11+ city and 13/14 highway. I want to make it more 14/15+ on highway.
@Boerseun I just got my RC speedometer calibrator today, I'll install it tomorrow when the light out. I should get a clearer picture of how my mileage really is.
@The_Bob88 Thanks! Looking forward to it!
@ostm282 The diameter of the tire manufacturer are probably basing it on is the spinning diameter. As the tire spins it quickly it stands taller. You may have seen it on some vintage drag race videos. But, that's just a speculation. I just calibrated my RC calibrator to 295.70.18. I'll compare it to my Garmin GPS and Phone GPS to see if there are any errors, if there is, I will calibrate it with the actual tire diameter after.

16 mpg was my best on cruise control going south on I95 towards Daytona with 275.65.18 averaging 74 mph for 80 miles. If I get 15 mpg with my current setup, it will be golden. I already got a quote back from SCS, I'll wait for the another group buy.



Thanks everybody!

 

In that case, tire manufacturers are just like dudes... They exaggerate measurements to make a sale before the customer finds out the actual size.

Although I've never had a chick whip out a measuring tape then decide to walk out after we already got that far

 

2020 Toyota Tundra SR5 4x4 with Toyota Safety Sense

I just installed Rough Country/Hypertech speedometer calibrator this morning after updating the firmware and inputting my parameters. Factory size 275.65.18 and new 295.70.18 (34.2"). Speedometer now reads 1-2 miles over gps and radar, which is okay by me. But if I entered the actual diameter of the tire when I measured it, 33.75it would have been dead on.

But, there's always a but. On my way home, I set the cruise control to 75, and speedo and gps reads 79mph. Whoa!!! slow down, set the cruise to 72 and that locked it to 75.

I called Rough Country tech support and they said that it does not show in their system or Hypertech's website if it's compatible. They are offering my a complete refund it I return it.
I called Hypertech to see if they are going to do an update, and they said they have to look at the sales if there is a demand for it before they can do anything else, but eventually, they will get into it. When I mentioned about the dynamic cruise control, they said, they still have not figured that out.

Hypertech/RC works, but set your cruise control and adjust base on the speedometer, not the cruise control speed.

So far so good.

 

I had my Cooper AT3 XLT's installed yesterday in a 295/70/18 and I love the new look!! My previous stock tires (275/65/18) were 31" in diameter and these new tires finished at 33 3/8" so I gained a bunch in height and width. As a refresher, I have the front lifted/leveled 1.5" with spacers and I put 1.25" Spidertrax wheel spacers on all four corners which pushes my stock rims out the perfect amount. The rear end of the truck is stock. Like most others running this size tire, I only had to custom trim the plastic piece on the inside of the bumper. I have plenty of room on the body mount side. I might have to trim or bend the skid plate underneath but I have it removed right now so we'll see. As far as the tire performance, I can only comment on how quiet these things are for having such an aggressive tread pattern (compared to the stock tires). We'll see how they sound once they have some miles on them but my god they're silent. Here's some before and after pictures
....

 

Hi everyone. I have a 2017 CM, everything stock, and was thinking of pulling the trigger on the XLTs soon. I have 2 questions:

1) I am planning on buying the OEM TRD off road alloy wheels to put on my truck, and was looking at getting 275/70R18's. Will i be able to fit those on the new wheels without rubbing issues?

2) Might be a noob question, but i currently have the stock steel wheels. Will i need to get different lugs for the OEM TRD off road alloy wheels?

Any input would be appreciated.