Narrower tires on wheel ? 255’s replace 265’s ?

Once I get my Medicine, you can do any dang thing you want.
YEP!!!

 

As long as the rim width is in the range of the tire you want, sure.

keep in mind that the “70” is the aspect ratio- the diameter is based on a percentage of the width; so with a narrower tire, you will also have a slightly smaller diameter one as well if that aspect ratio stays a “70”

 

Tire Rack and others have calculators to help you achieve your original diameter. I've done less tread width but same OD when I've had an alt set of wheels shod with dedicated snow tires. Handling's not as good but that was also going from ultra performance to snow tires.

 

Use the resources at Tire Rack to determine the overall circumference of the stock tire package. Then compare the available 255s and see which one departs the least (that's still good quality, not Hankook, Fuzion or something). It could be a 255/75 would be a better substitution.

Mike, the limit for me is, I don't know the width of your stock rim. If your stock tires really filled out those wheels, then you can go smaller. But in some instances the wheel is wide enough, that you really can't go any smaller than what you already had.

I like a smaller, narrower tire for ice and snow. And torrential rain as well.

 

Yessir, but as stated above the aspect ratio can come in to play. Going from a 265/70r17 to a 255/75r17 would put you almost a half inch taller, or a 255/70r17 a half inch smaller overall. Also tire availability may be something to think about. That factory size will be more common across the board if you ever had an flat that couldn't be patched.

 

yes. just make sure the load rating is right and find someone who won't squawk about doing it.

 

Lower size number, same aspect ratio means a smaller tire. Make sure your existing tire size is overly ample for the wheel width - with the tire sidewall bulging out away from the wheel.
Otherwise you start going in the above direction, where the new tire is essentially too narrow for the wheel. This is where you get into the deepest trouble when downsizing.

 

Right.

Some shops get weird about changing away from stock sizes. They're terrified of claims back against them - just don't use such people to start with.

Tire Rack's info gives you a W number and sometimes the next smaller size, instead of a 94, is a 91 and in theory at least, this lesser rated tire cannot carry the same amount of freight.

 

You can run narrower but should adjust the aspect ratio to keep the same diameter and the tire must be capable of the same load specifications. The diameter thing is important for 4x4/AWD vehicles as the spare has to be changed if you go to a different tire diameter to avoid damage to the drivetrain. Individual vehicle manufactures will state the allowable variance for that.

 

https://tiresize.com/comparison/

 

That chart shows 245/75 17s are almost exactly the same diameter. I did not check load ratings though - that would be important on a truck.

 

I think these Subaru drive systems, other various SHAWD type systems are finicky about tires with mismatched effective diameters. It confuses the software, and it is the reason some of them don't come with a small "donut" spare at all. I know if I run mixed, radically different circumferences on these Saabs, I get a Traction Control warning light. It surely messes with TPS systems. But I am thinking Mike's truck is liberated from a lot of those gizmos.

In a universe of drivers where there's virtually no "bottom" in terms of the worst of the worst drivers, it is hardly a surprise that manufacturers try to discourage certain things and they probably intervene before they really need to. But some consumers will try anything - and I guess we have to defend these people from their self destructive impulses.

 

This. In PA to pass state inspection the vehicle must have the size tire that is indicated on the driver side door panel. Most garages don't want to veer from this due to liability issues. If you have a friend or "know a guy" that will do it you're likely to be ok.

 

So you are saying that if my 1978 F350 has 7.50/16 listed on the door that I can't legally switch to a metric sized tire ? I have this very truck .

 

I think the nuttiest thing is, when a PA car dealer takes a vehicle in as a trade, and then has an out of state customer waiting with check in hand, the vehicle still has to pass through PA state inspection even though the new owner has no plans at all to register or even use the vehicle in Pennsylvania.

Then you gotta scrape the dumb sticker off that foolish location they've chosen for it in your field of vision. WTF?

By the way there is ZERO evidence on the vehicle I bought in Reading, that the inspectors discovered anything of importance, or that they communicated any information along the stream to the consumer. This is just a cash grab, nothing more.

 

Subaru has about the tightest specification in the industry relative to matching tire diameters for their Symmetrical All Wheel Drive system.

The sticker location in PA is specified by the PA Department of Transportation, in the lower left corner of the windshield. There's no flexibility in that. Some technicians are not, um...as careful as they should be...when they install it, however. When my Ascent was delivered to me in 2018, the stickers were on an angle. I made them agree to correct without cost that as a condition to signing the final papers. Yes, it was an early morning prep as the vehicle arrived the night before on my factory order, but lack of coffee was not an acceptable excuse to me for this...I'm WAY to anal to have something like that angled in my vision relative to the window, hood and road. LOL

 

One thing to beware of - modern traction control, stability control and things like ABS and AEB are callibrated for the rolling diameter, as the wheel sensors speeding up and slowing down determine the effectiveness of the brakes. Could be the difference between a 'Depends' change and ER/panel shop.

Hence the tyre placard, you work out the manufacturer specs wheels from 16" from the base to 19" on the full house sport/lux turbo model, but the effective rolling diameter will be the same.

Plus the well-documented Ford Exploder tyre problem has made the industry gunshy about this issue.

 

The 4x4 is no different as far as all tires the same diameter. What would be binding for the fixed system is wear for differentials.

 

I'm sure that car's bagged.