225/45 18 vs. 255/40 18 for 2019 Premium

[Bernie]

Has anyone tried this yet?

Spec. Sidewall Radius Diameter Circumference Revs/Mile Difference
225/45-18 4.0in 13.0in 26.0in 81.6in 777 0.0%
255/40-18 4.0in 13.0in 26.0in 81.8in 775 0.2%

it works out to 1.181 inches or 9.84% wider if my math is right which means the contact patch will be maybe 12-15%? more and only a half inch wider on the wheel face it shouldnt look like a balloon... any thoughts? constructive or otherwise

 

[eflyguy]

What size rim does the manufacturer of the specific tire you're looking at say they are OK for?

 

[Bernie]

It's the factory wheel. So I am going to ignore their opinion.

 

[Hapa88]

Has anyone tried this yet?

Spec. Sidewall Radius Diameter Circumference Revs/Mile Difference
225/45-18 4.0in 13.0in 26.0in 81.6in 777 0.0%
255/40-18 4.0in 13.0in 26.0in 81.8in 775 0.2%

it works out to 1.181 inches or 9.84% wider if my math is right which means the contact patch will be maybe 12-15%? more and only a half inch wider on the wheel face it shouldnt look like a balloon... any thoughts? constructive or otherwise

Contact patch will be roughly the same. Keep the stock size and just buy a more aggressive (stickier) tire. More info on why can be found here:
You Thought You Knew - Tire Contact Patches

When you install wider tires without changing anything else, the size of the tire's contact patch (i.e., the rubber touching asphalt) stays relatively constant. That size is based on a tire's overall diameter, inflation pressure, and the weight acting on it. Installing fatter tires widens the patch, but it also shortens it front-to-back. Because of this, cornering gains can be offset by diminished straight-line traction, including braking and hydroplaning resistance. The increased mass and friction can also translate to slower lap times and a drop in fuel economy.

If you want to improve cornering grip, you're better off switching to a higher-performance tire of the same size. Buy right, and you'll get a stiffer sidewall for crisper turn-in and steering feel, as well as a stickier rubber compound and a tread pattern focused on dry grip.

Width won't do it. Merely increasing the width of a tire doesn't increase the area touching the pavement. It just makes it a wider, shorter patch.

A bigger donut. If other vehicular factors remain constant, increasing a tire's overall circumference is the only way to enlarge the contact patch. Of course, your car's body and suspension were designed around a specific tire circumference. Changing it might cause more problems than it solves.

Pressure and weight. Reducing air pressure or increasing the weight on a tire increases the size of the contact patch. But again, there are drawbacks. Some poor engineer has already fought this battle: Keep the stock size and just buy a more aggressive tire.

 

[ScottWB]

Has anyone tried this yet?

Spec. Sidewall Radius Diameter Circumference Revs/Mile Difference
225/45-18 4.0in 13.0in 26.0in 81.6in 777 0.0%
255/40-18 4.0in 13.0in 26.0in 81.8in 775 0.2%

it works out to 1.181 inches or 9.84% wider if my math is right which means the contact patch will be maybe 12-15%? more and only a half inch wider on the wheel face it shouldnt look like a balloon... any thoughts? constructive or otherwise

Thanks for asking the question, I noticed the sidewalls were practically flat and was wondering when time to install new tires I could go with something wider. Although Adrian has a very convincing argument... I have only had the car for a week so replacement tires are a while off.

 

[SOCAL2.0]

any thoughts on staggered tires stock (2.0 Premium) fronts 225 45 18 with 255 40 18 rears

any advantage or drawbacks?

 

[ScottWB]

Contact patch will be roughly the same. Keep the stock size and just buy a more aggressive (stickier) tire. More info on why can be found here:

Just from a appearance stand point you have to admit the 255's would look pretty cool thou.

 

[Gtecko]

edit :

Iam interested if anyone tried this with a square set up

 

[Hapa88]

225/45/18 is the oem specs but I think it is quite the change ...

View attachment 31566

You mistakenly compared the wrong size.
He was asking about 255/40/18 which is about the same diameter overall as the OEM.

 

[Gtecko]

You mistakenly compared the wrong size.
He was asking about 255/40/18 which is about the same diameter overall as the OEM.

look at me and my fat fingers here haha, I edited my post, thanks !

 

[Bernie]

any thoughts on staggered tires stock (2.0 Premium) fronts 225 45 18 with 255 40 18 rears

any advantage or drawbacks?

I would be concerned about the difference in rolling resistance and possibly damaging the differential if you used a staggered set up.

 

[eflyguy]

I would be concerned about the difference in rolling resistance and possibly damaging the differential if you used a staggered set up.

You're kidding, right? Those two have *exactly* the same diameter..

 

[Bernie]

No.
I have first hand experience with a customer that had her 4wd vehicle have a flat less then a mile from my shop I put the factory spare on because the tire for her 1100 mile vehicle was not available. She blew the rear diff in 19 miles.

You don't mix tires on a 4wd AWD .

I don't like this transmission 's logic nor do I trust it or what is behind it. I have a serious clunk in the diff... and the shaft is tight.

I love the car ... and my original post was has anyone done it. Based on looks and there was someone above who answered all the contact patch questions.

So yes, I am serious because I need tires and was wondering. Bought my Blue Danube on Jan 19. 34279 miles.

Not trying to start a flame war if you want to talk ...pm me. Anyone

 

[Manaz]

No.
I have first hand experience with a customer that had her 4wd vehicle have a flat less then a mile from my shop I put the factory spare on because the tire for her 1100 mile vehicle was not available. She blew the rear diff in 19 miles.

You don't mix tires on a 4wd AWD .

I don't like this transmission 's logic nor do I trust it or what is behind it. I have a serious clunk in the diff... and the shaft is tight.

I love the car ... and my original post was has anyone done it. Based on looks and there was someone above who answered all the contact patch questions.

So yes, I am serious because I need tires and was wondering. Bought my Blue Danube on Jan 19. 34279 miles.

Not trying to start a flame war if you want to talk ...pm me. Anyone

It depends how the AWD system in place operates. Incidently, a blown rear diff means the issue was to do with left to right, not front to back, and was likely due to a locked rear diff.

With a traditional transfer case and locked centre diff, I totally agree.

Even with setups like Subaru's AWD (with various styles of viscous centre diff), having different rolling diameters front to rear can cause grief.

But it appears, from what I was repeatedly told when I first recommended against a non-squared setup on an AWD Stinger, that the setup Kia runs allows some level of variation, as they (apparently) sell a staggered setup AWD model in some markets.

Regarding your clunky diff, the Stinger has had rear diff issues - again, that's nothing to do with the AWD setup (or the transmission for that matter), as it happens on RWDs as well (in particular it seems the ones with the LSD centre).

 

[SteveCo]

But it appears, from what I was repeatedly told when I first recommended against a non-squared setup on an AWD Stinger, that the setup Kia runs allows some level of variation, as they (apparently) sell a staggered setup AWD model in some markets.

All the cars sold in Canada have AWD, and all the V6 cars are sold with Michelin PS4 tires on staggered OEM 19 inch tires/rims. There is no 18" factory option on the V6 cars, they only are sold on the 2.0L GT-Line trim.

Many of us swap the staggered 19s out for the winter, to a square setup using 18" rims/winter tires. Personally, very happy with the performance of both so far.

 

[Bernie]

Manaz you rule. That is the most reasoned reply ever.

But I have been to several Michelin tire schools experienced many things and have raced many miles in rally. That said, grip and equal grip is so important. I had a driver who could feel .5 pounds in pressure and knew which tire. ... right? So crazy but it makes a difference... play on words intended.

 

[SOCAL2.0]

can't see the harm in staggered tire set up for my 2 wheel drive 2.0 premium I do need extra traction as I can spin the rears on streets with low traction. It has happened to me unexpectedly and is kind of embracing.