18's on AWD

[alscall]

KU31's may be cheap for 235/40R18 but they are $350 for 235/45R18 at Bobs. Bobs quoted me $370 for the evo12 in 235/45R18.

vlad: I've only ever run the 235/45/18 profile on my AWD.

Shop around a bit because it seems like you're being royally ripped off! My hankooks cost me a little less than $1100 fitted & my KU31's cost similar.


There's plenty of cars with this profile stock now, so they don't cost what they used to; Bob Janes even had a Yokohama in that profile for about $300 when I was looking about a year ago.

There's a guy on fleabay that list the KU31's for about $500 a pair; maybe look there?

[Oggy]

Phew - fleabay to the rescue of stressed wallets. KU31s are available (1 listing) of "235-45-18 98W KUMHO ECSTA KU31" for $193.50 each. = $774 a set.
There's also some ACCELERA brand, same size qty 4 for $567 if you want to risk anyones safety

[RussianMax]

When I had 235/40/18 on my car, when I first got my 18s and didn't know much about tyre sizes, it threw my speedo 5km/h out. It showed 5km/h MORE then I was actually doing since the circumference is smaller then speedo is programed to. So per wheel revolution the car travels shorter distance then it would have on stock wheel. Now on 235/45/18 its 1km/h or so underreads. 225/45/18s are rather few in my experience with only Toyota Aurion and Nissan 350Z using that size. Hankook K416 with the right load rating is available but I'm not sure on price.

[G-ManVRXAWD]

Hey Guys, New here. Running Lancer VRX wheels 18x7 with 235/40/18 and with 44psi speedo only out by 4km/h at 100k's acording GPS which I use in preference to the speedo anyway. Here in Victoria if your car is manufactured before 2006 then the Govt/Vicroads says they will allow a 10% tolerance regarding your speed. Manufactured after 2006 and they only take into account 3% tolerance which is BS really cause tyres are not the same between manufacturers despite saying they are the same size.
BTW, I run 235/40/18 Jinyu tyres. They are made in China but have a high silica content making them soft but they are weraing OK after 12 months and grip as good as any tyre I have used. They cost me $86 each fitted and balanced! Check out the guy at https://www.tyremagic.com.au/ in Sunshine. He is the imprter for the Jinyu tyres. So cheap yet very good IMHO.

[RussianMax]

G-ManVRXAWD The pressure of 44 PSI is way above something that any tire shop would ever recommend. Unless its an Extra Load tire. In case of such pressure the tire tread will bow out and you'll be riding on a reduced contact patch which will affect your braking and handling. On top of that once tires warm up the pressure will rise up even further by roughly 2 PSI. I run 40 PSI and thats an absolute limit to what I'd ever put into a car road tire.

I myself have stripped off a few Jinyu tires at my store and can't say I was impressed with what I saw. Just for the sake of safety I wouldn't put anything on my car which isn't known. I run Goodyear Eagle F1 Directional 5 on my car and it handles like on rails. Worth every cent.

Out of curiosity How did you measure the grip? You referring to handling? I'm asking because if you are talking acceleration then your AWD system would make the tire virtually irrelevant. Unless its a Yellowsea

Being 235/40R18 I assume the speedo overreads by the mentioned 4km/h?

[Dave]

44psi :/

[TiMi]

get the wheels balanced and your car aligned
also try and find a flat tape measure (like one to measure people for clothes) that you can wrap around the wheels, and measure the circumference of the tyres at equal pressures.
Too much of a difference could cause it to want to go one way or the other, and I don't think driving with uneven rolling diamaters is good for your diff(s)

also-

tyre contact patch size is directly related to weight pushing on the wheel and tyre pressure
2000 pound car, 4 wheels, 500 pounds/wheel.
50 pounds per square inch of pressure = 10 square inches the pressure has to push against the ground with to balance the 500 pound on that wheel
25 pounds per square inch of pressure means it flattens out into a 20 square inch contact patch

higher pressures give faster cornering response, and better fuel economy

pressures to high from the manufacturers standars cause the tyre to baloon out, and press the middle against the road first, causing uneven wear and wearing the centre of the tread down faster

pressures too low cause the sidewalls to start pushing the outer treads against the ground rather than the tyre pressure pushing it against the road, wearing away the inner and outer edges of the tyre before the middle.
pressure also holds the tyre bead against the rim faces, hard cornering with not enough pressure to hold it in place could dislodge the tyre from the rim.

[trx850]

Got it sorted by buying some second hand low km Continental Contact 3 in 245 40 18 spec- just sensational with this combination- have had on for a couple of months now- steers so well and very predictable and stable as well. Very happy finally.