Outer Limits 4x4 Board

Hi,
I am trying to find the largest 7.50R16 tyre available in Australia. So far the largest I have come across is the Motorway Gripper at a diameter of 819mm. If I can find one that is 825mm in diameter I won't need to worry about an engineering cert for 33" tyres.

I'd like to have the diameter spelt out in a broucher or online so that I can keep it in the truck as proof that the tyres I have are acceptable.

Cheers,
David

How does this work for you?

Bridgestone Light Truck Textile Bias Jeep Service Pattern 7.50-16 114L 827mm OD

This will help me too. DO you have a spec sheet for the bridgestone Jeep service???

On a related note, anyone know what the largest 9.00x16 is/was? I think some of them were almost 37"

cj wrote:How does this work for you?

Bridgestone Light Truck Textile Bias Jeep Service Pattern 7.50-16 114L 827mm OD

Hi CJ,
Sounds exactly like what the doctor ordered. Do you have a URL? I tried a google search for what you entered but didn't have any luck.

Thanks,
David

I am pretty sure the bridgestone jeep service crossply is no longer available, so I doubt it will be listed on the web (at least not on an official site).

ISUZUROVER wrote:I am pretty sure the bridgestone jeep service crossply is no longer available, so I doubt it will be listed on the web (at least not on an official site).

I found some pictures of them

http://antti.rauramo.com/hj45/kuvat/200 ... nkaat1.jpg

If we could get a spec sheet, scan it and put it up on the web somewhere I reckon that could help a few people out.

Replying to myself here but I thought it might interest someone.

I did some looking around and found some threads on exploreoz that deal with this issue:

http://www.4wdaustralia.com.au/Forum/Ar ... /10049.asp
http://www.exploroz.com/Forum/View.asp? ... 26PN%3D121

From what I understand a 7.50R16 is offically 812mm in diameter. ADR 23 allows for a 3 percent difference between the official diameter and the actual manufactured diameter.

Therefore a 7.50R16 could be anywhere between 787mm (31") and 836mm(32.9") in actual diameter and still legally be classed as a 7.50R16.

Taking this into account you should legally be allowed to run up to a 851mm(33.5") tyre on a vehicle plated for 7.50R16.

Of course you should all check this stuff out for yourself before you decide what you can get away with.

Cheers,
David

Very interesting stuff...

So it looks like you could legally run up to almost a 34" if your vehicle was originally specced with 7.50x16's!!! Since many radial tyres are a bit smaller than their theoretical diameter this could be interesting.

We need copies of ADR23 and the ADR tyre size standards (ARD23 also?) to confirm this and have it in writing.

It would be interesting to see someone argue this, because there have been threads here before about people being given a defect notice for 33" tyres on a vehicle originally specced with 7.50's.

Anyone have copies of the relevant ADR's they can scan??? I am also interested in the ADR specs for a 9.00x16.

I think from memory that the firestone SAT 7.50 x 16 was a large tyre around 33" mark

Werent the defects for 33" tyres because they were 12.5" wide on 8" rims and tyre manufacturers specs say minimum 8.5", which is also illegal.

33.10.5.15 on 8" rims with correct offset is legal i believe, as is 285.75.16 on 8", for vehicles that had 7.50r16 on or on placard.

Cheers
Daryl

ISUZUROVER wrote:We need copies of ADR23 and the ADR tyre size standards (ARD23 also?) to confirm this and have it in writing.

Apparently you can purchase the complete collection of ADR from http://www.dotars.gov.au/transreg/str_subscriptions.htm for $23.55. If someone already had a copy that would be preferable.

ISUZUROVER wrote:It would be interesting to see someone argue this, because there have been threads here before about people being given a defect notice for 33" tyres on a vehicle originally specced with 7.50's.

Did they get done for the height, width or both? 33x12.50R15 tyres would still not be acceptable from my understanding as 12.5" wide tires are not permitted on 8 inch wide rims. I am planning on fitting 33x11.20R16 (285/75R16) tyres which are legal on 8 inch wide rims.

I believe there is plenty of 'interpretation' that goes on when it comes to rules and regulations. Rules are often interpreted differently on different occasions. If you are not informed of the rules and regulations you have to go with the interpretation of the supposedly informed officers of the law.

ISUZUROVER wrote:Anyone have copies of the relevant ADR's they can scan??? I am also interested in the ADR specs for a 9.00x16.

The tyre diameter details are in the Australian Tyre and Rim Standards guide. Hopefully your local tyre dealer would have a copy of this (perhaps not in Deutschland) otherwise you could try calling the Australian Tyre and Rim Association directly (they're in the Melbourne White Pages).

I might see if I can run this passed a friendly law enforcement officer.

Cheers,
David

Werent the defects for 33" tyres because they were 12.5" wide on 8" rims and tyre manufacturers specs say minimum 8.5", which is also illegal.

.............................................................................................................

Some manf now specify 8" rims for 12.5 tyre widths, Cooper, Goodyear, BFG aust.

Bazzle

bazzle wrote:Werent the defects for 33" tyres because they were 12.5" wide on 8" rims and tyre manufacturers specs say minimum 8.5", which is also illegal.

.............................................................................................................

Some manf now specify 8" rims for 12.5 tyre widths, Cooper, Goodyear, BFG aust.

Bazzle

Hi Bazzle,
I don't think that the allowable tyre/rim combination is dependant on what the manufacture specifies but rather on whether that combination is permitted by the Australian Tyre and Rim Association. I don't believe that 12.5" tyres are permitted on 8" wide rims.

I believe the ADRs specify that the maximum allowable rim width is 10" so you might be able to get your car engineered for 10" rims.

In Victoria you can go up to 1 inch wider than the widest rim specified by the vehicles tyre placard which may allow you to use 9" wide rims on some vehicles without engineering. I haven't seen many (any?) 9" wide rims on the market.

Cheers,
David

grimbo wrote:I think from memory that the firestone SAT 7.50 x 16 was a large tyre around 33" mark

Nah, not the case. My partly worn 7.50's were barely any taller that your old 7.00's last time Christover was up @ my place and we compared them. Not much over 30.5". Maybe about 31.5 new.

They are a fair bit wider than most other 7.50's, hence their reputation in the UK for excellent floatation.

goodyear custom xtra grip's are very tall 7.50 x 16. Not sure if they are still available though.