changing wheel offset = changing vehicle track. Problem?

[Shonky.]

I am looking at some aftermarket wheels.

After a lot of measurement and staring at the car with finger in belly button I have decided I want

19x8.5 et27 and 19x9.5 et40

my question is, is there a problem with changing the vehicle track to get the desired appearance?

I figure standard wheels are et36.5 so I will be:

increasing the front track by (36.5-27) x 2 = 19mm

and

decreasing the rear track by (40-36.5) x 2 = 7mm

What impact will this have on handling?

I understand that an increase on rear track is sometimes done to aid stability, so what is the impact on reducing it slightly, but more important changing the relationship between front and rear track by (19+7) =roughly one inch?

[Kieron]

If i'm not mistaken, it's illegal to do this or there might be permissible increases allowed. I would have thought increasing front track would put additional stress on the stub axles/outer wheel bearings etc?

I increased the front track of an XC Falcon GS I had (for track purposes) and it improved handling, but steering felt like it was a pendulum.

[madmelon]

In NSW, track changes are limited to 26mm I think. Apart from that, is it really possible to get a 27mm offset front wheel into the wheel well without hitting the guard? Similarly, is it possible to get the back wheel in without hitting suspension and brake stuff? I'm pretture sure 27.5mm was the factory offset for rear wheels on FPV vehicles and T series, so you're actually losing a lot more track than you think.

Might be worthwhile getting the rear offset and trying it on the front to see if anything hits before actually buying.

[Shonky.]

Originally Posted by madmelon

In NSW, track changes are limited to 26mm I think. Apart from that, is it really possible to get a 27mm offset front wheel into the wheel well without hitting the guard? Similarly, is it possible to get the back wheel in without hitting suspension and brake stuff? I'm pretture sure 27.5mm was the factory offset for rear wheels on FPV vehicles and T series, so you're actually losing a lot more track than you think.

Might be worthwhile getting the rear offset and trying it on the front to see if anything hits before actually buying.

My car is +36.5 all round

They don't do staggered offset anymore.

and I am sure clearance will be fine. On the front of the car the outside edge of the rim will move out by about (36.5-27) + 6.35 (half the increase in rim width) = 15.85

On the rear of the car the inside edge of the rim will move in by about (40-36.5) + 19.05(half increase in rim width) = 22.55 which should be ok also

Just worried about changing the handling characteristics of the car for the worse

[mik]

i think increasing the track/tyre width may beneficial in some ways , but it may also increase the kick back in the steering over bumps and undulations, possibly increased tram lining, a bit more shock felt on rough roads, on my 50`th my young brother saw me looking at some sexy wheels on his mates hotrod, sometime later on my birthday he borrowed my car for a couple of hours and brought it back with the bigger boots and wheels on, the above characteristics where noticed, mind you mine has firmer shocks on it, but i noticed the same characteristics on his soarer when upped the wheel size with standard shocks.

[Shonky.]

In QLD you are allowed to increase track by up to 26mm

and NOT allowed to decrease it at all

http://www.tmr.qld.gov.au/Safety/Veh...fications.aspx

So for peoples interest that means for an FG, having a factory offset of 36.5, you can run a wheel with offsets between et 23.5 and et 36.5

While people with et40ish and above rims probably don't mind the legal aspect are you able to comment on any changes you noticed when going to a narrower track?

Would love to hear from the guys running 10 inch rims on the back of FGs as you generally must be rocking offsets in the higher 40s, say around et45 or higher

[JC]

Originally Posted by shonkymofo

In QLD you are allowed to increase track by up to 26mm

and NOT allowed to decrease it at all

http://www.tmr.qld.gov.au/Safety/Veh...fications.aspx

So for peoples interest that means for an FG, having a factory offset of 36.5, you can run a wheel with offsets between et 23.5 and et 36.5

While people with et40ish and above rims probably don't mind the legal aspect are you able to comment on any changes you noticed when going to a narrower track?

Would love to hear from the guys running 10 inch rims on the back of FGs as you generally must be rocking offsets in the higher 40s, say around et45 or higher

What are you defining as the track measurement? It is supposed to be "Wheel track is the distance measured across an axle from the centre line
of one tyre tread to the centre line of the opposite tyre tread." By going a wider rim, even with reduced offset, you are always increasing track. The only time you wouldn't is if you reduce the offset by more than the width increase in the rim, but in those cases you are likely to scrub the tyres on the bodywork or they will stick out past the bodywork.

A 0 offset rim means the hub mounting face is equal to the rim centreline. A 36P offset means the hub mounting face is closer to the outside edge of the rim and is usual for FWD.
A 36N offset means the hub mounting face is closer to the inside edge of the rim (not too many cars run this type of offset, if any).

So, if you increase rim width by 1.5" (38mm) over standard, half of that is 19mm, so you could go down as low as 17mm offset without affecting track.

If you increase rim width by 0.5" (13mm), you can increase offset (to 42mm) and still be legal but you may hit the front strut assembly with the inside of the tyre. You could also reduce offset by 12mm (to 24mm) and still be legal as this will cause a track increase.

[EB#]

Hey Shonky, try checking out Tocchi's thread on his FG XR8....
http://www.fordforums.com.au/showthread.php?t=11243471

This guy has run all sorts of different wheel combinations and
in racing applications too. I'm sure a PM his way would sort you out
with some additional advice.

[Sprint]

I have 30mm more track on the front of my ba when i use my Grid R's 18x9.5+20

and 40mm more on the back 18x10+15.

Rules!

Never go wider on the front than the back or face huge oversteer.

Never go less track than standard full stop!.

Dont go massive track increase on the back but keep the front standard, will make for bad understeer.

try to keep track on both front and rear withing 10mm with a preferance to wider on rear if anything.

increase track may be illegal and will cause more strain on bearings,rims and suspension components but will dramatically increase cornering abilities.