285/75x16 Coopers on '92 80 series TD

Submitted: Friday, Apr 02, 2004 at 09:04
ThreadID: 11755 Views:3087 Replies:8 FollowUps:8
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Time for new tyres, would like to go up to the 285/75x16 Cooper AT or ST (still undecided) from the 265's currently on at the moment.
A few questions....
My 80 suffers chronic turbo lag under 2000rpm, so the taller tyre would obviously effect the gearing (by 7% according to previous posts), anyone running the same tyre on the same car, whats your opinion in actual drivability...slip the hell outta the clutch?!
Any one know if this size tyre would be legal in SA for the 80 series?
Does anyone in Sydney know where to get a good price? Matthews in 7 Hills quoted $288/tyre...
Thanks for any input...
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Reply By: Member - Jeffrey - Friday, Apr 02, 2004 at 10:08

Friday, Apr 02, 2004 at 10:08
Hi Mrdesmo,
I'm running coopers at the moment at the size your thinking about,I live in the sevo area you can have a look at my st after approx4500 kms and not much 4wding on them,..but dont they GRIP I lifted my wheels momentarily negoiating ruts to small mountains..you know what I mean and when they touched down I nearly got whiplash,the blocks seem to chip easy.but I run them on a Patrol
All The Best In Health And Wealth
Jeffrey (AKA JD)
AnswerID: 52914

Follow Up By: mrdesmo - Friday, Apr 02, 2004 at 13:42

Friday, Apr 02, 2004 at 13:42
Hi Jeffrey,
Great name...and initials (same as mine!)
I'm currently in the process of packing up the house to move interstate, so may not have a chance to have a look at your car. Been waiting 6 weeks for a reply to a job interview, they ring back last Wednesday and say "you got the job, you start in 2 weeks".....b@^#%$s
You running ST's or AT's?

Cheers
Jeff
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FollowupID: 314720

Reply By: Member - Captain (WA) - Friday, Apr 02, 2004 at 10:29

Friday, Apr 02, 2004 at 10:29
I had 31" BFG tyres on my 80 series (non-turbo) and went to 33" BFG (same as 285/75R16). I found the gearing change a positive thing as it always had relatively low gearing.

But there was a HUGE difference in off-road performance. In WA beach sand, where I previously had my tyres down to 20 psi just to be able to get through, I was able to get through on 40 psi (a test - not normal practise).

I changed to the 285/75R16 Cooper ST's when I got my GU and rekon they are better than the BFG T/A KO's IMHO (I previously had a great run with BFG's, but never found the KO series the same). I never found the change in gearing a problem on the GU (originals 265/70R16), in fact it was not noticeable (but I only did 35kms before changing the tyres!).

While you "may" notice a gearing change, I would not hesitate to change the tyres as the huge offroad performance gains more than outweighs it.

Cheers

Captain
AnswerID: 52917

Follow Up By: Member - Don (QLD) - Friday, Apr 02, 2004 at 10:52

Friday, Apr 02, 2004 at 10:52
Captain,
Which did you find to be noisier the BFG or Cooper St.
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FollowupID: 314708

Follow Up By: Member - Captain (WA) - Friday, Apr 02, 2004 at 11:09

Friday, Apr 02, 2004 at 11:09
Hi Don

The BFG TA KO's are quiet but the Cooper ST's are relatively noisy, not a problem at all, but you can notice them if listening out for it.

If the windows are up, you can hear the Coopers on smooth bitumen wheras rough bitumen is noisy regardless of tyre type and there is no real difference (Cooper tyre noise is from the wind on the lugs).

But given the noteably better off-road grip of the Coopers, I would not hesitate to go the Coopers again. Only thing is would go for the ST'c, which are supposedly better chip resistance. I have not had an issue wiith chipping, but would get them anyway.

One thing that really suprised me was that when driving on gravel, the BFG's really machined gunned the inner mudguards with stones, whereas the Coopers hardly pick up a stone in comparison, but have better grip at the same time!

Cheers

Captain
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Follow Up By: mrdesmo - Friday, Apr 02, 2004 at 13:37

Friday, Apr 02, 2004 at 13:37
GDay Captain,
Thanx for your reply, I believe the non turbo has lower gearing (diffs?) than the turbo model 80 series, I find even trying to get up steep driveways sometimes takes a bit of slipping the clutch with the standard tyres on, hence my question of drivability with larger tyres. I'm about to move house, and where we will be staying has a steep driveway/hill to climb, so the right tyre choice now will save me clutch dramas later on!

Cheers
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FollowupID: 314718

Reply By: Member - Don (QLD) - Friday, Apr 02, 2004 at 10:59

Friday, Apr 02, 2004 at 10:59
I put 285/75/16 on my 80 Series and found them to be good.Before that i had just the standard 265/70/16. Since getting the 80 i had put a DTS Turbo on and i notice the turbo takes at about 2200rpm.Which sometimes can be a drama.No probs with the clutch yet.(touch wood).I am not sure of the legals in SA, but in Qld i think it is 15% over original tyre size. But the pros outweigh the cons.
Good luck
AnswerID: 52920

Follow Up By: mrdesmo - Friday, Apr 02, 2004 at 13:50

Friday, Apr 02, 2004 at 13:50
Gday Don,
Excuse my ignorance, but is 285 15% larger than 265 in tyre terms? According to the tech data the the difference is tad over an inch...

Cheers
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FollowupID: 314721

Follow Up By: Member -Bob & Lex (Sydney) - Friday, Apr 02, 2004 at 15:20

Friday, Apr 02, 2004 at 15:20
It's about 8% but in NSW you can only go up 5%. Do'snt matter unless somthing happens .
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FollowupID: 314727

Follow Up By: Member - Don (QLD) - Saturday, Apr 03, 2004 at 09:17

Saturday, Apr 03, 2004 at 09:17
Yeh i am not sure i thought i read that somewhere in the archives.I guess you have to check with the local transport department just to be sure.
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FollowupID: 314811

Follow Up By: Member - Rohan K - Monday, Apr 05, 2004 at 11:47

Monday, Apr 05, 2004 at 11:47
It is 15 mm, not 15% and the 285/75/16 is not legal without an engineer's certificate.
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FollowupID: 314963

Reply By: Member - Jeffrey - Friday, Apr 02, 2004 at 14:01

Friday, Apr 02, 2004 at 14:01
Hi Mrdesmo,
I'm running st..LT 285/75R16 M+S.
All The Best In Health And Wealth
Jeffrey (AKA JD)
AnswerID: 52939

Reply By: Member - Allan - Saturday, Apr 03, 2004 at 00:13

Saturday, Apr 03, 2004 at 00:13
Hi Mrdesmo, I have 285/75x16 tyres and I blamed them for making the chronic turbo lag you describe worse. I eventually had the injector pump adjusted while on the dyno. It is now a totally different vehicle to drive with far better low down torque. The larger tyres actually improves gearing (I always thought they were a bit low geared).
Don't be afraid of the 285/75's and don't put up with the turbo lag - it can be cured for very little money.
AnswerID: 53018

Reply By: Member - Dave (Pilbara) - Saturday, Apr 03, 2004 at 11:16

Saturday, Apr 03, 2004 at 11:16
onen thing to note is the 265's are a tougher tyre. They are equivilent to 10 ply. The 285's are a lighter construction. I took this into consideration when I brought my 265 ats and have not regretted it. The other thing to note is the 265's have a very straight side wall and the footprint on the ground is almost the same as a normal 285. Ie tread width is not much less. I travle a bit on very sharp rocky roads so this was important tom it may not be to those who don't have the same usage. I run mine on a 100 series turbo and have noticed a minor difference in the take up but the 100 has far less lag than the 80.
AnswerID: 53048

Reply By: Bob Y. - Qld - Saturday, Apr 03, 2004 at 20:19

Saturday, Apr 03, 2004 at 20:19
G'day Jeff,

We have 265's BFG AT's on 80 series multi valve, and it has plenty of lag, so haven't gone to bigger tyres. Previously, we had a 90 model 80 series turbo, with 31x10.5R15's on it, and it would really boogy, but at cruising speed, we were always looking for the next gear.

Suppose you could always fit an intercooler, to get some more grunt.

Good luck in the new job.

Hooroo...
Seen it all, Done it all.
Can't remember most of it.

Lifetime Member
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AnswerID: 53098

Reply By: Bob et Joëlle - Sunday, Apr 04, 2004 at 10:30

Sunday, Apr 04, 2004 at 10:30
We got a lot of help on the legals from the answers to our post 11692 - the insurance issue could be a bit of a problem no doubt - it is often someone else that causes the prang !

B & J
AnswerID: 53132

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