Are your larger tyres legal?

[Robbo]

Hey drafty is gunna get booked just on the colour alone the rest will pale into insignificance

[murcod]

Thought some people on here might enjoy a laugh- below is the response I just received from an engineer when inquiring about fitting larger tyres to my Feroza. I want to go to a 235/75R15 from a 225/70R15 ( a huge increase of 37.5mm diameter!)

Hi, fitting of larger tyres than specified on the tyre placard has several ramifications:

1. It increses the rolling diameter and thus the speedometer and odometer are not accurate.

In your case the increase of 37.5 mm above the diameter of the largest std. tyre, 697 mm is 5.3%.

Speedometer accuracy limit is 7% from the ADR's. Thus you would need to recalibrate the speedo.

2. Larger tyres raise the vehicle centre of gravity, 18.8 mm. Minimum ground clearance for 4-WD specification is 200 mm thus an increase of 10%. This will reduce the vehicle side slope stability and cornering power which is not desirable as 4-WD's are unstable enough as original.

3. The larger rolling diameter reduces the available braking torque, again not desirable, and a 5.3% reduction is not good. Going larger than the manufacturers rated maximum would negate the braking SAustralian Design Rule compliance. The vehicle would need to be re-tested to prove compliance and this test is very extensive thus very expensive. My brake testing equipment is not adequate for ADR testing, but is suitable for doing parts of the test such as the brake fade test Transport SA specify for modified cars.

4. The change in gearing will change the engine speeds (lower) used for the ADR emission test and 5.3% could make the certification null and void. Again, to retest is expensive, around $3000 if you could get access to one of the motor company or consultants emission test facilities.

5. The change in gearing would also invalidate the ADR 28/00 noise test certification as this is very critical for engine speed in the drive-by test. Static noise test is obviously not affeccted.

Overall, without recertification, the vehicle can be defected readily, and if involved in a crash, insurance may well be invalidated.

It is legal to ADR 24/00, however, to increase the tyre diameter by 15 mm greater than the largest tyre size shown on your tyre placerd, the tyres you want however are bigger than this.

[bundytunna]

try TSIC insurance company
they r based in adelaide and insure ppl with modded 4bs
only catch is i think(dont quote me) u have to be affiliated with a 4wd club
fees r preety cheap too ive heard

anyone who runs muddies is pretey much fugged
susp and body lift?
like stressed sed
if u dont tell the insur comp bout ur mods and u have a stack u r basically Farked
they wont insure u one bit
my mate had a VS commy and slid into a tree wrote the back of the car off he had to take off evry mod b4 the insur comp came to evaluate him
he took off cold air intake wheels seat even stickers and u know what he got pinged for ?
the bloody exhaust tip yes TIP
they sed it was not standard and increased performance thus makeing the car unroad worthy?
he had to pay for everything
rule No 1
NEVER TRUST INSURANCE COMPANIES

[big_nissan]

What is the largest tyre size and suspension lift you can run on a GQ in QLD?

[big_nissan]

Legally i mean.

[murcod]

Bundytunna, it's the state laws and ADR's that are the problem- the only legal way around them is to get an engineer to certify the mods and then have the vehicle inspected (with no guarantee it will pass!)

[murcod]

What is the largest tyre size and suspension lift you can run on a GQ in QLD?

Try looking here for the answers: http://www.transport.qld.gov.au/qt/driv ... ations.pdf

A quick scan showed the +15mm max rule for tyres- but I couldn't see any limit on lifts?