Picked up a set of 18X8.5 second hand- w/ 3 tyres- 245x40x18- pretty cheap and pretty worn- found another tyre- different brand just to see if they were going to clear everything OK and work on the car. Tried them on and am getting some quite significant tram tracking through the steering- now feels quite nervous even on the straight. Sure cornering steering response is very good, but the nervousness at the straight ahead is, well, quite nervous. Is this typical of fitting 18's. Just like to clarify before spending $ on buying decent new tyres to fit the 18's. Does look good on the 18's. So far clearances don't appear to be a problem- close on the rear struts and guards but do actually clear on standard springs. 245x40 are about as close as I can get to the 215x60X16's

Get them balanced, and an alignment. And the wider tread does feel like a bit of nervousness but it's just picking up more imperfections on the road surface.

245x40x18 are only 11mm smaller than the stockies, so no problem there.
I've got 235/45/18 on mine and no problem either.

But did you know that the 8.5" width wheel probably isn't legal? From memory, 8" width is as far as FWD and AWD cars can go, unless wider is fitted from factory.

When my tyres were new, they drove just fine, didn't notice any difference in behaviour, but now they have about 10,000kms on them and the steering does wander and twitch a bit when the road isn't smooth

Yes i know that 8.5 is pushing the boundaries- but right price and drive like a grandpa- rarely attach attention form Mr Plod- so unless they are going to look really close????

balance and alignment plus check pressure I increased mine a little and it lessened the tramlining

225/45 or 235/45 are perfect for the 18 inch rims. Even better then 245/40 although since you are running 8.5 inch you are probably right to have 245s.

Wheel alignment is very important especially if you lowered your car as that has affected your suspension geometry.

Wider rims and tires ALWAYS tramline a lot more then narrow.

By the way. Whats the offset on your rims?

Could also be the tyres that are causing that tramline effect more so than what you had fitted prior. I for one know the Dunlop SP Sport MaxxGT tyres I used to have on the VR-X tramlined more and felt twitchier than the Continental ContiProContact tyres fitted after, and the Maxxis MAV1's prior. That's down to how the tread pattern effects the way the tyres fall into the grooves and so fourth in the road.

By the way. Whats the offset on your rims?

Bin a while seens I bin on- sizes are 18 8.5 w offset of 38- cheap crap tyres (I think that is an economy brand that comes out of a province in china) 245 40 18.

So, no clearance issues on the inside - but do they sit perfectly,(legally), inside the guards?

So, no clearance issues on the inside - but do they sit perfectly,(legally), inside the guards?

Very close on the rear end inside- just fit my little finger between tyre and strut but has not had a rub issue- but have not had the car with heavy load in it yet- also only on standard springs/ shocks- have some KYB shock to put in the back end when I get the chance to- no issues at all on the front evan at full lock either side- still on standards springs/shocks up front too. 245 40 18 are closer to original diameter than the more popular 235 40 18. When money comes available would go with the 245's I think.

As RussianMax said, original OD is 664.4mm. 225/45R18 (max 8" rim) gives 659.7mm and 235/45R18 gives 668.7mm. The reason you can fit your finger in the rear is due to smaller OD (653.2mm) which gives extra 5.6mm clearance. The upper arm angle does not change with weight in the car. So that gap is always maintained.

Bear in mind that 225/45R18 tyres are more expensive than 245/40R18 and 235/45R18 is even more expensive. Especially those with at least 95 load rating.
245/40R18 tyres will only set you back $200.00
225/45R18 tyres will set you back $300.00
235/45R18 tyres will set you back $350.00 (cheapest bein Kumho KU31)

I currently have 225/45R18 on 18x8 with 35+ offset. Planning to fit the Kumho 235/45R18 later this year.

Also note the 235/40R18 tyres are illegal on the AWDs due to load rating and OD differences.

Thanks for that info vlad- I have been using one of the web online tyre/rim calculators to work out sizes- I have been able to find some 235 40 18's with above 95 load rating but outside diameter is down around 645mm which IMHO is probably getting too big a speedo difference plus outside the legal limit in some states- 245 40 18 (still affordable) 653mm outside diameter- so a little bit smaller in OD but within legal limits. Around the $200 a corner is pretty reasonable but not into ploughing really big money into this- Know a guy with current falcon f6g turbo- replacement factory spec tyres- $525 a corner- over 2 grand for a full set.

Find this web site very helpful
http://www.rimsntires.com/specs.jsp

Find this web site very helpful
http://www.rimsntires.com/specs.jsp

That site was free to use until recently. Now it only gives you a small sample of results.
This one (http://www.1010tires.com/tiresizecalculator.asp)lets you compare speed and OD etc between OEM and up to four other different sizes.

As RussianMax said, original OD is 664.4mm. 225/45R18 (max 8" rim) gives 659.7mm and 235/45R18 gives 668.7mm. The reason you can fit your finger in the rear is due to smaller OD (653.2mm) which gives extra 5.6mm clearance. The upper arm angle does not change with weight in the car. So that gap is always maintained.

Bear in mind that 225/45R18 tyres are more expensive than 245/40R18 and 235/45R18 is even more expensive. Especially those with at least 95 load rating.
245/40R18 tyres will only set you back $200.00
225/45R18 tyres will set you back $300.00
235/45R18 tyres will set you back $350.00 (cheapest bein Kumho KU31)

I currently have 225/45R18 on 18x8 with 35+ offset. Planning to fit the Kumho 235/45R18 later this year.

Also note the 235/40R18 tyres are illegal on the AWDs due to load rating and OD differences.

vlad: KU31's shouldn't cost anymore than $1,000 fitted & balanced. (That's what I paid over 3yrs ago!) Check out the Hankook Ventus Evo12's - a far better tyre, IMHO & a similar price. Correct load rating too. :)

Also note the 235/40R18 tyres are illegal on the AWDs due to load rating and OD differences.
Please explain. I fail to understand why you state they are illegal, what makes an AWD any different to any other Magna that rolls out of the factory on 215/60R16's? I also don't understand the load rating issue, as every set of 18" tyres I've ever owned have been 235/40R18 over both my 3rd gens, and all of them have not only met but exceeded the load and speed rating requirements. Regulations may be different in SA, but there's certainly no issue with legalities here in Vic with that size.

Lugo, regardless of load ratings, I have some bad news for you.

you said 215/60/16 (OD = 664.4mm on paper) and 235/40/18 (OD = 645.2mm)
These 2 tyres have a difference in their diameter of 19.2mm - that pus the 235/40/18 outside of the allowed range which is + or - 15mm in NSW.
I think in QLD they may be allowed to go +15mm and -25mm which would make these OK, but AFAIK only in QLD.
What are the rules for Vic?

Cheers, Oggy.

vlad: KU31's shouldn't cost anymore than $1,000 fitted & balanced. (That's what I paid over 3yrs ago!) Check out the Hankook Ventus Evo12's - a far better tyre, IMHO & a similar price. Correct load rating too. :)
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.

Please explain. I fail to understand why you state they are illegal, what makes an AWD any different to any other Magna that rolls out of the factory on 215/60R16's? I also don't understand the load rating issue, as every set of 18" tyres I've ever owned have been 235/40R18 over both my 3rd gens, and all of them have not only met but exceeded the load and speed rating requirements. Regulations may be different in SA, but there's certainly no issue with legalities here in Vic with that size.
In Victoria it is also +/- 15mm. The ADR states +15/-26mm but each state has their own interpretation. Plus 235/40R18 will visibly look small for the car and leave lots of wheel well gap.

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. lol

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?

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 :D

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.

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 http://www.tyremagic.com.au/ in Sunshine. He is the imprter for the Jinyu tyres. So cheap yet very good IMHO.

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 :P

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

44psi :/

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.

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.