Tire question......

[Goldeneagle]

How much bigger is a 255/75-15 than a 235/75-15? Got into an argument with the manager at NTB yesterday. I think he was just mad because I only wanted 2 instead of 4.

[EarleyBird]

The first number is the width of the tread. The second number is the height of the sidewall and is 75% of the tread width. The 255's are wider than the 235's and the sidewall height is 75% on both, so the 255/75/15 tire will be wider and taller. There are websites that will give you the exact measurements.

[Sackett]

.8" wider and 1.18" taller.

[DJM]

.8" wider and 1.18" taller.

This really depends on manufacturer.While the specs are the same ,the actual dimensions can be very different.

DJ

[Goldeneagle]

The truck originally came with 235's. Someone put 255's on it and I want to go back to the original size. Right now I can only afford 2 and want them on the back. He said they could put them on the front but not the back unless they put all 4 on. He claimed it would mess up the drivetrain. I told him that was for 4 wheel drive's and mine is 2 wheel drive and it won't hurt anything. He bucked up on me and told me he had been in the tire business for 10yrs and knew what he was doing. I told him I have been driving longer than he has been living and to get my truck off the lift. He asked what they were going to do with the 2 tires I special ordered and I told him one of his workers could stick them up his rear and I walked out. Back in the day we always ran 2 different sizes and never hurt a thing. No more NTB for me.

[Skullworks52]

20mm difference in height.

[bbuck8]

Result of lawsuits. Everybody gotta cya.

[carp]

15mm or .59 in height
20mm in width

[CletusBodeen]

255 divided by 25.4
Multiply that by .75
Multiply by 2
Add the diameter.

That formula will give you the tire height for any tire.

[SB09]

Result of lawsuits. Everybody gotta cya.

This is right.

What year model truck and type do you have? The Chevy's have what's called a stabilitrack system. If you put two different diameter tires on them you get lights like a christmas tree on the dash.

[riverbowman]

This might get you close.

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

[denowt]

The truck originally came with 235's. Someone put 255's on it and I want to go back to the original size. Right now I can only afford 2 and want them on the back. He said they could put them on the front but not the back unless they put all 4 on. He claimed it would mess up the drivetrain. I told him that was for 4 wheel drive's and mine is 2 wheel drive and it won't hurt anything. He bucked up on me and told me he had been in the tire business for 10yrs and knew what he was doing. I told him I have been driving longer than he has been living and to get my truck off the lift. He asked what they were going to do with the 2 tires I special ordered and I told him one of his workers could stick them up his rear and I walked out. Back in the day we always ran 2 different sizes and never hurt a thing. No more NTB for me.

You should've ask him if they offer free tire rotations.
Buy the tires, then ask for your 1st free rotation, lol.

In all seriousness though, your truck would look funny with the front sitting slightly higher than the rear.
Just curious though, why are you so dead set on placing the smaller tires on the rear?
Just my opinion, but whenever I buy only 2 tires, I always want my newest tires on the front.
If I blow a rear tire going 70mph, I have a decent chance of stopping safely.
If I blow a front tire going 70mph, not so much.

20mm difference in height.

The mm number is the width, the 75 is the %height of the sidewall.
20mm difference in width, 15mm difference in height.

[Goldeneagle]

This is right.

What year model truck and type do you have? The Chevy's have what's called a stabilitrack system. If you put two different diameter tires on them you get lights like a christmas tree on the dash.

It's a '93 Silverado. Don't think it has all the fancy stuff on it.

You should've ask him if they offer free tire rotations.
Buy the tires, then ask for your 1st free rotation, lol.

In all seriousness though, your truck would look funny with the front sitting slightly higher than the rear.
Just curious though, why are you so dead set on placing the smaller tires on the rear?
Just my opinion, but whenever I buy only 2 tires, I always want my newest tires on the front.
If I blow a rear tire going 70mph, I have a decent chance of stopping safely.
If I blow a front tire going 70mph, not so much.



The mm number is the width, the 75 is the %height of the sidewall.
20mm difference in width, 15mm difference in height.

The front tires are newer than the rear. Rears are weather cracked pretty good. It's 2 wheel drive and I want some tires on the back that will do better in the dirt than the street tires that are on it now. I'm planning on replacing the fronts in a month or so.

[SB09]

It's a '93 Silverado. Don't think it has all the fancy stuff on it.

The front tires are newer than the rear. Rears are weather cracked pretty good. It's 2 wheel drive and I want some tires on the back that will do better in the dirt than the street tires that are on it now. I'm planning on replacing the fronts in a month or so.

Yep, none of that fancy stuff in a 93 model for sure. Only thing I can come up with is liability reasons. May be better suited going to a small individually owned place. At least they're more likely to do what you want them to do and not what corporate wants them to do.

[denowt]

It's a '93 Silverado. Don't think it has all the fancy stuff on it.

The front tires are newer than the rear. Rears are weather cracked pretty good. It's 2 wheel drive and I want some tires on the back that will do better in the dirt than the street tires that are on it now. I'm planning on replacing the fronts in a month or so.

Ahh, that makes sense.
I didn't think about you changing tread patterns also.