Thread: Engineering for larger tyres.

as another side of it.....

if the engineer who did the cert gets revoked all of his certified work can be revoked and require a re-inspection, same goes for your road worthy.

ITs not usually done becasue the amount of time it takes to track down all the defunct work an engineer has done is prohibitive but it will turn up ocassionally when you go to put new plates on a vehicle and have to have the roadworthy redone.

I think from memory that you can get away with 25mm oversized wheels in all circumstances and 50mm of spring lift. Im not sure of the rules for body lift.

Originally Posted by Slunnie

Xav the ACT has adopted the NCOP in all areas AFAIK
http://www.rego.act.gov.au/assets/PD...0the%20ACT.pdf

So in accordance with this he can run tyres which are 50mm larger in diameter without approval.

http://www.infrastructure.gov.au/roa...g_3Feb2006.pdf

What he said - don't know where I got the part about total lift.

Discos come with 29" tyres standard?

Originally Posted by isuzurover

What he said - don't know where I got the part about total lift.

Discos come with 29" tyres standard?

When you spend time going looking for loopholes, there are heaps in the NCOP. It'll certify up to 150mm combined lift, but not over this irrespective of engineering approval. You don't need to certify a lift which is within 1/3 metal to metal suspension travel, but you do need to if the lift is over 2". Interestingly, on a Discovery 1/3 metal to metal is about 70mm. Likewise, I'm not sure if you run 2" bigger dia tyres and a 2" suspension lift, both of which don't need approval individually if you will then need approval as the combined lift is 75mm.

Discos tyres are 29". I would be inclined to work in nominal metric measurements though as there seems to be a lot of misinformation bandied around when people are converting metric to US measurements. I'm sure I read in AULRO recently that the standard Disco wheel size is 28" and a 235/85-16 is a 31" or similar - both of which are incorrect.

Originally Posted by Slunnie

It'll certify up to 150mm combined lift...

Discos tyres are 29". I would be inclined to work in nominal metric measurements though ...

235/75-16

Ah - that was it, thanks. 50mm BL, 50mm tyres, 50mm springs.

If you can get a copy, it would be best to go by the "standard" diameter in the Tyre and Rim Assoc. Standards manual, to work out the +50mm.

Originally Posted by isuzurover

Ah - that was it, thanks. 50mm BL, 50mm tyres, 50mm springs.

If you can get a copy, it would be best to go by the "standard" diameter in the Tyre and Rim Assoc. Standards manual, to work out the +50mm.

Sorry, I made a tyre size error in my previous post.

The standard tyre is 235/70-16. (approx 29")

Thanks for the replies. Not at all what I wanted to hear but...... Maybe when I'm in a better mood I'll tell the story.

Thanks again.

The other thing to take in mind is that an engineers cert doesnt mean that legally it can use those size tyres etc etc it means that the vehical as deemed to be safe if fitted with those tyres and it is up to the relevent pen pushers weather or not they will deem them legal....which they usually dont.

It was me who said that the standard D1 size was 28 and the 235 85 16 was 31, that was rough sizes, the standard rubber on an early d1 was 225 75 16 and on alloys they went to 235 70 16 both of which by my converter come in at 29" but in reality in BFG AT (which is the only tyres I can attest to first hand) are closre to 28" at 35psi measured accross the face so work that out.

My BFG AT 235 85 16 are 31.5" (just on) measured the same way.

I dont know how they actually work out these sizes but I know that Simex sizes are not all that accurate, neither are Silverstones and obviously not BFG so where is it as far as legally, do they measure them or do they take the size and work it out that way?......I dont think we will ever know.

Find out who he is talking to down here. I know of 1 patrol engineered on 35's so 33's on a disco shouldn't be any problems.

If he is talking to the dickson inspectors tell him to go talk to a engineer. they are cranky old men down there. I had a mate take a brand new ba xr8 and get failed. He was working for a ford dealer and had to get the darker tint ticked off, car came off the truck and got the tint then was driven to dickson.before it went to the customer and they failed it for it being to low.