18x8 Maximum tire width?

[bwagman]

Hello,

I'm new to this forum and looking forward to some valuable insight into the Kia Stinger. I understand that my question may have been addressed in a past thread, but I made conscious effort at searching before posting, so please don't roast me lol, but I came up with nothing. Simple question...What is the maximum tire width I can go on the stock 18x8 wheels (square)? 225s are just too tiny. Don't want to screw up speedo or sacrifice handling. Any thoughts, any of you actually run 245s or 255s? Thank you in advance. Ben

 

[MerlintheMad]

Howdy and welcome. I agree, the 225 does look a bit underfed in the back. The 8" wide wheel will take a recommended maximum width tire of 245. (the 8.5" wide wheel already has the max recommended width of 255)

 

[RM7]

It's not an exact science, because each tire manufacturer has their own rim-size limit according to their own sizing. So while Michelin says you can do 245 on an 8", others say the max is 235. Having had to go with Michelin 295s instead of the stock front 285s on my other car, I can confirm they work out a little narrower than the size number indicates.

The optimal rim range is 9-9.5 for 245 tires. But again, it will usually work on 8".

While you *can* fit other tire sizes, this gets increasingly harder for the shop. They will sometimes flat out refuse, from concerns of liability. Sometimes they will, but if it's a hard fit, they can end up damaging your wheels as they put everything into getting the tires on the rim. My advice here is verify from the tire manufacturer that it's ok for that size rim, that will keep you out of issues with the shop usually.

I have a spreadsheet I've used to calculate the difference in diameter and such. 245/40 is about a quarter inch less in diameter than stock 245/45, but the closest ratio to have the tires the same diameter as stock. I think the difference is around 1%, not going to screw up speedo significantly.

I'm leaning towards getting the 19 x 8.5 or 9" to run 255s square, probably next summer, using the stock rims for my winter tires. I have a set of 225/40s that will fit. Just under an inch difference in diameter, will lower my car half an inch and increase wheel gap by half an inch and require 3.5% correction, but they are studded and in excellent condition, perfect for winter.

 

[bwagman]

I found that on the tire rack website it says one up size you can go 225 45 18 and 255 40 18 on the stock 18s (which I believe are 18x8 square). Could this be wrong?

follow up - I called TR and they said the 255 would need an 8.5 inch wheel. So that answers that.

 

[RM7]

I found that on the tire rack website it says one up size you can go 225 45 18 and 255 40 18 on the stock 18s (which I believe are 18x8 square). Could this be wrong?

follow up - I called TR and they said the 255 would need an 8.5 inch wheel. So that answers that.

Yes, that is general information and you need to consult the tire manufacturer directly to see what their limits are. That's exactly what I meant. Here is a chart I made for my other car. The dark green is the optimal range. The light green is the "one size off" that TR is talking about. That is not the end of the conversation though, as again, each tire manufacturer has their own different criteria, so you may be able to get an additional size to fit on the rim and be perfectly fine. TR is just stating their general/standard line, but it's not true for each situation. If you are shopping by "car", you are going to get the results you are talking about. If you shop by size, then you can go back and see.

If Michelin says they are ok, they are ok. Buy the tires from costco and have them installed at costco. AFAIK, Michelin seems to always allow one side wider.

 

[oddball]

Check the specification sheet for the tire you want. That will tell you the manufacturer's min and max limits for that tire. Anything else is just a rule-of-thumb.

Almost all 245's work fine on 8" rims.

 

[JSolo]

Considering going with a wider square setup on a gtline, 245/40/18.

Looking at tire rack's tire specs for oe,

https://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Potenza+RE97AS-02&partnum=245VR8RE97AS02XL&vehicleSearch=true&fromCompare1=yes&autoMake=Kia&autoYear=2022&autoModel=Stinger%20GT-Line%20AWD&autoModClar=

803 revs/mile in stock size

Compared to continental dws06+

https://www.tirerack.com/tires/tires.jsp?tireMake=Continental&tireModel=ExtremeContact+DWS+06+Plus&sidewall=Blackwall&partnum=44YR8DWS06PXL&tab=Specs

808 revs/mile in 245/40/18

Overall diameter - cont. 25.7" vs 25.9" for the bridgestone. The continentals are slightly smaller diameter (by .2") compared to stock. What's .2 inches, ~5mm or 6.4/32's. The speedometer will actually read slightly faster than one is going - miles will accumulate faster. How much faster?

5 revs per mile difference or less than 1% (.622%). So at 60K indicated, the car will actually have traveled 59625 miles if my math is correct? Relatively insignificant.

Edit, another option is the michelin pilot sport as4 in the same 245/40/18 size - https://www.tirerack.com/tires/tire...wall=Blackwall&partnum=44YR8PSAS4XL&tab=Specs

revs per mile here is 804. Nearly identical to stock. These tires are heavier than stock (26lb vs 24lb). The dws06 is 22 lb (2lb less than stock). I really think all of this is negligible. I do however believe mpg will decrease slightly with any performance oriented tire, even in stock size.

 

[RogueIV]

FWIW I'm running 245/45r18 up front on my car. This is a bigger OD than stock but it doesn't seem to have much affect on my speedometer . Fits on the 18x8 fine.

 

[JSolo]

^^What's in the back, size and tire model?

 

[RogueIV]

^^What's in the back, size and tire model?

275/40r18 General G-Max RS they are the same OD as the fronts. those are on 18x9.5 wheels though.

 

[JSolo]

That's some meaty tire! I'm sticking to a square setup, will likely just want some more grip. Don't think I need something that wide on the 4 banger.

I'm running 235/50/17 on an accord right now. Other than a lacking suspension and weak engine, the car corners surprisingly well once settled. 99% of the driving around here is all straight lines. Chicago area is a very grid like environment. Only fun areas are on/off ramps.

 

[RogueIV]

That's some meaty tire! I'm sticking to a square setup, will likely just want some more grip. Don't think I need something that wide on the 4 banger.

I'm running 235/50/17 on an accord right now. Other than a lacking suspension and weak engine, the car corners surprisingly well once settled. 99% of the driving around here is all straight lines. Chicago area is a very grid like environment. Only fun areas are on/off ramps.

For sure they're on the chonky side. I have the 3.3t. I was going to do square but couldn't really get the size i wanted. These have been doing well for me though.

 

[JSolo]

I got an opportunity today to put a few miles on the car (~250) on various interstate and windy backroads.

These are roads I've traveled for many years, am extremely familiar with and have a pretty good feel for in terms of cornering speed. The stinger with the stock re97as-02 just didn't feel right on the tighter high speed stuff. Seemed like there was too much understeer and I could almost hear the tire squealing - lacked a planted feel. Body roll wasn't too bad (used to the accord having to "settle" into the corner).

I'm guessing this stock tire is more of a touring tire than performance? Had michelin pilot sport as 3+ on the 4 cyl accord. Entry speeds were faster and much more confident (albeit no drive out power).

Did other folks experience similar results which were improved with a better tire? I'm tempted to just get the AS4's, but seems like a waste with just a few months of summer left (chicago). I drive like gramma in the winter.

 

[RM7]

I got an opportunity today to put a few miles on the car (~250) on various interstate and windy backroads.

These are roads I've traveled for many years, am extremely familiar with and have a pretty good feel for in terms of cornering speed. The stinger with the stock re97as-02 just didn't feel right on the tighter high speed stuff. Seemed like there was too much understeer and I could almost hear the tire squealing - lacked a planted feel. Body roll wasn't too bad (used to the accord having to "settle" into the corner).

I'm guessing this stock tire is more of a touring tire than performance? Had michelin pilot sport as 3+ on the 4 cyl accord. Entry speeds were faster and much more confident (albeit no drive out power).

Did other folks experience similar results which were improved with a better tire? I'm tempted to just get the AS4's, but seems like a waste with just a few months of summer left (chicago). I drive like gramma in the winter.

IMO, it's a really lackluster tire in a pretty narrow width. The Stinger isn't heavy compared to it's contemporaries, but it's a relatively big sedan and it's going to need a decent amount of tire underneath to reach full potential. As an example, my little Elantra GT N-line also had 225s. Ok, now scale up the vehicle size and weight...it should get bigger (wider) tires...but it doesn't. I think those same bridgestones came on my BMW, in the same width. In that case, I went to 245s, but not just any 245s, but good dedicated summer performance tires. IME, that's really where you gotta go.

Yeah, I automatically assign any AS tire as a "touring tire". It's just never going to be up there like a PSS or PS4s.

If you can afford, get summer and winter/AS tires. Life is too short to not have summer tires on your primary fun-ride IME. Too many cars come with AS and up here in the North, AS sucks in the summer and it sucks in the winter. It just sucks all around. Give me a car with either summer or winter tires...but don't give me this useless AS crap IMO. You could look at it as "it kind of does ok all the time", but that's not really true in the winter on ice, they suck there. They also suck pushing to the limit in autoX and other handling situations.

I personally went with a high performance AS on my 18.5s to get a 255 width tire, with the intention of wet-autoX, but I don't need this to be my primary summer fun car. It will be used in the winter on winter tires. The 255 tires handle well and no complaints, but it's not to the level of a good summer tire. I'm a few ticks above stock with the tires and sway-bars. Again, no complaints. It's a GT type car and these changes make it more sporty and responsive.

 

[JSolo]

I'm leaning towards the pilot as4 in a 245/40/18 size. According to tire rack its the same revs per mile as the bridgestone re97as-02 in 225/45/18. Odd how that works out. Different size but same overall diameter. They specify 7.5 - 9.0 " rim size, so 8" should work.

I rarely drive during snow events (working from home, never actually). I had dedicated winters with the G. In 8 years those tires barely saw 4K miles. Roads are cleared within a day around here. If the need to drive during really bad storms does arise on a regular bases I'll get dedicated winter wheels/tires (in 225 size ) then.

Bulk of use is urban. There's the 2 or 3 long annnual roadtrips down south to real roads. I don't drive over 50% down there anyway as roads are unfamiliar. I had enough close encounters with wildlife on two wheels to know better. I push enough to have fun, but not to end up sideways. "Mature adult" driving style (subjective I know).

As I mentioned earlier, I had the as 3+ on the accord in a 17" size with 50 profile. Very confidence inspiring tire even on a car with a lackluster suspension. I could throw the car around a corner knowing once it settled, the line would keep. Very predictable. There's a cloverleaf onramp in the area with a recommended speed of 30. I could do it at 40 quite comfortably in the accord. If it performed so well in that size, a shorter sidewall on an inch larger wheel should be even better.

Some of the other threads on here complained of a vibration with the stock bridgestone. The only vibration I experience was when driving on an asphalt road that had been stripped but not yet repaved. It got very loud.

 

[JSolo]

So I've more or less convinced myself the stock tires have to go (after 200 miles of driving).

My usual tire place of choice is discount tire. Been dealing with them for 2 decade for various vehicles.

My concern is their lift equipment. This car sits pretty low and the skirts seem are nearly level with the pinch weld that runs the length of the car. Should I just bring some pucks with?

Their equipment seems similar to a quickjack system.

 

[JSolo]

FWIW I'm running 245/45r18 up front on my car. This is a bigger OD than stock but it doesn't seem to have much affect on my speedometer . Fits on the 18x8 fine.

A 245/40/18 will have slightly (barely) less sidewall than the 45 above. Are you having any rubbing issues? When cornering aggressively? I'm pretty sure rear will be fine but it's the front I'm concerned about.

Is a gt 18x8" wheel the same offset as a gt-line 18" wheel?

Is this correct? Kia Stinger 2021 - Wheel & Tire Sizes, PCD, Offset and Rims specs

Shows 34mm offset for both gt (3.3) and gtline.

 

[RogueIV]

A 245/40/18 will have slightly (barely) less sidewall than the 45 above. Are you having any rubbing issues? When cornering aggressively? I'm pretty sure rear will be fine but it's the front I'm concerned about.

Is a gt 18x8" wheel the same offset as a gt-line 18" wheel?

Is this correct? Kia Stinger 2021 - Wheel & Tire Sizes, PCD, Offset and Rims specs

Shows 34mm offset for both gt (3.3) and gtline.

Correct, GT 18s are the same as the GT line. I have no rubbing at stock rideheight and don't forsee any when i goto lower it, whenever i get time to do it. These cars are pretty accommodating to tire size changes.