Listed tire size vs actual tire size

ConMan08 · August 31, 2022

Hi all,

Everything that I have read from the interwebs, either here or on aftermarket manufacturers website is that a 33" tire is the tallest tire you can fit on a leveled GM truck. But the 33" tire, is that based on the listed tire size or the actual tire size?

I'm currently running 275/70R18 BFG ko2s which is listed as a 33.2" diameter tire but under load and at approximately 40psi the tire is closer to a 32" tall tire. I know BFG is worse than others when it comes to their actual tire size vs their listed tire size but it still got me thinking, can I go into the range of listed 34" tall tires and not have any rub issues?

I would really like to run a 295/70R18 (34.4" diameter) (which I know does not come in a Ko2) but will not do so if it requires metal work. Assuming I have a similar diameter loss as my 275/70s so I'm expecting them to run right at 33". I don't mind trimming some of the felt but I'm not looking to cut or take a hammer to the inside of my wheel well.

Any input would be greatly appreciate!

HeySkippyDog · August 31, 2022

You're going from a 275/70R18 to a 295/70R18.

275 to 295 is just more width by 20mm. It's not taller. Both have a 70 sidewall profile.

I don't see the point of this, but then again a lot of people make their trucks squat or they slam them to where they can't go over a speed bump.

It's Tim · August 31, 2022

12 minutes ago, HeySkippyDog said:

You're going from a 275/70R18 to a 295/70R18.

275 to 295 is just more width by 20mm. It's not taller. Both have a 70 sidewall profile.

ya, it is:

https://tiresize.com/comparison/

newdude · August 31, 2022

1 hour ago, ConMan08 said:

Hi all,

Everything that I have read from the interwebs, either here or on aftermarket manufacturers website is that a 33" tire is the tallest tire you can fit on a leveled GM truck. But the 33" tire, is that based on the listed tire size or the actual tire size?

I'm currently running 275/70R18 BFG ko2s which is listed as a 33.2" diameter tire but under load and at approximately 40psi the tire is closer to a 32" tall tire. I know BFG is worse than others when it comes to their actual tire size vs their listed tire size but it still got me thinking, can I go into the range of listed 34" tall tires and not have any rub issues?

I would really like to run a 295/70R18 (34.4" diameter) (which I know does not come in a Ko2) but will not do so if it requires metal work. Assuming I have a similar diameter loss as my 275/70s so I'm expecting them to run right at 33". I don't mind trimming some of the felt but I'm not looking to cut or take a hammer to the inside of my wheel well.

Any input would be greatly appreciate!

Someone on this site a while back fit 295/70 on stock Trail Boss wheels on a TB. I "think" it was stock height? If I can find it I will try and link it. I believe the tire OEMs measure the dimensions as mounted on a wheel to max inflation of the tire and no vehicle load on them.

32 minutes ago, HeySkippyDog said:

You're going from a 275/70R18 to a 295/70R18.

275 to 295 is just more width by 20mm. It's not taller. Both have a 70 sidewall profile.

I don't see the point of this, but then again a lot of people make their trucks squat or they slam them to where they can't go over a speed bump.

Uh. Its taller. Aspect ratio aka the "70" in 275/70R18 is a percentage of the width of the tire. So 275/70, the sidewall height aka the aspect ratio is 70% of the width of the tire. 295/70 is taller.

Edited August 31, 2022 by newdude

newdude · August 31, 2022

3 hours ago, ConMan08 said:

I would really like to run a 295/70R18 (34.4" diameter) (which I know does not come in a Ko2) but will not do so if it requires metal work. Assuming I have a similar diameter loss as my 275/70s so I'm expecting them to run right at 33". I don't mind trimming some of the felt but I'm not looking to cut or take a hammer to the inside of my wheel well.

Any input would be greatly appreciate!

One more thing to add, I can definitely tell you 305/70 on stock wheels rubs from beyond half to full lock on flat ground, either the wheel well or the mudflap but it was def rubbing.

Edited August 31, 2022 by newdude

ConMan08 · August 31, 2022

Thanks newdude for the response. I'm currently on stock wheels with a 35mm spacer and don't have any rub issues (running HALO Boss Coilovers cranked to 2" of lift). I have set of 18x9 Racelines on order that are -12, I'll be ditching the wheel spacers once I get those mounted.

I will more than likely stick with 275/70s as I do want to retain the ability to take it down a trail and not worry about stuffing my tire and ripping my wheel well liner out or damage a control arm or tie rod. I suppose the proof is in the pudding, there is probably a good reason why most people stick with 275/70R18 or 285/65R18 on their leveled GM trucks.