33" MTR's or 31" ST's

Submitted: Tuesday, Jan 10, 2006 at 21:53
ThreadID: 29547 Views:1815 Replies:7 FollowUps:0
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Howdy all,
I bought a set of 33" MTR's a while back but have only recently fitted them to my 1990 80 series. I used to run the standard 31" x 15" Cooper ST's but as they were wearing a bit thin i decided to try something bigger. At the same time i fitted 3" lift coils and new Koni shoks. I'm about to put in a 3 degree castor kit to straighten the geometry out a bit......but here is my actuall question:

Has anyone else gone from standard rubber up to the 33" and noticed the reduction in performance (because of changed ratio's to final drive) and general sluggishness? I havent noticed too much difference in fuel consumption when taking into account the speedo being out by about 6% (according to my GPS).

My camper weighs in at just over the tonne so i'm thinking of going back to 31" rubber, probably in the ST's as they seem to be an awesome all-rounder....

Any comments? (anyone game to?)

Cheers
NUTS!
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Reply By: revhead307 - Tuesday, Jan 10, 2006 at 22:32

Tuesday, Jan 10, 2006 at 22:32
This always comes back to personal choice...

however i would never go back to 31's after having 33's on the patrol.
Yes i did notice a reduction in top end highway speed...and a slight fuel increase.

However bigger rolling diameter and increased footprint make up for a multitude of sins.

not to mention they give that slight increase in clearance.

shame on you.

Rev
AnswerID: 147687

Reply By: Sarg - Tuesday, Jan 10, 2006 at 22:32

Tuesday, Jan 10, 2006 at 22:32
Yes. Probably won't notice any saving in fuel, as the engine is working harder under acceleration & offsets any saving at cruise from the lower revs.
Have a look at this & do your own figures.

http://www.dfw-tx4wd.org/Tech-Dept/Tech-Dept/gearstable.htm
AnswerID: 147688

Reply By: Truckster (Vic) - Tuesday, Jan 10, 2006 at 22:37

Tuesday, Jan 10, 2006 at 22:37
You will lose all round.

Lose power, larger diameter more to turn
Worse fuel, takes more to turn the larger heavier diameter.

How much did u pay for MTR's...?
AnswerID: 147690

Reply By: Member - Captain (WA) - Tuesday, Jan 10, 2006 at 23:03

Tuesday, Jan 10, 2006 at 23:03
Hi NissanNut,

I originally had 31" BFG TA's on my 80 series and went to 33". I towed my van (1.6T) regularly with it and while I noticed a marginal reduction in on-road performance, nothin that worried me (a 1HZ has NEVER been accused of being fast anyway!!!).

But the off-road performance increase was VERY noticeable. So much so that when I got my brand new GU, it went straight from the dealer to the tyre place and I had 285/75 (33") Cooper ST's fitted with only 00035km on the odo.

Could never go back to 31" after having 33" but YMMV

Cheers

Captain
AnswerID: 147695

Reply By: Member - Tony G (ACT) - Wednesday, Jan 11, 2006 at 13:24

Wednesday, Jan 11, 2006 at 13:24
I found that 32's were about the best all round tyre size.
AnswerID: 147779

Reply By: NissanNut - Thursday, Jan 12, 2006 at 15:06

Thursday, Jan 12, 2006 at 15:06
Thanks guys,
Lots of helpfull comments that ive almost come to expect from this forum, a tribute to you all. Cheers.

I think ill see out the 33", they cost me $200 each with about 80% tread second hand. I havent had a good opportunity to really test these tyres out off road, but hopefully ozy day long weekend will change that. That graph in the web link is very intersting, if i every get locker diffs i might look into changing the ratios to bring them back closer to standard final drive ratio.

Or, next set of tyres, i might try the 32"s,

like one of you said, comes down to personal prefference.

Thanks again,
NUTS!
AnswerID: 148051

Reply By: udm - Thursday, Jan 12, 2006 at 23:22

Thursday, Jan 12, 2006 at 23:22
I bought my 80lc with 31" (1 year ago), straight away got 33", yesterday I got 35" and I am never going back to either 31 or 33.

Now on 35´s, speedo´s out a fair bit, but I love the gearing, the 1hz (n/a) aint overreved at 100km/h anymore. And with the bigger rubber, you will feel the car drives smoother. In city driving you just have to forget you´ve got 5th gear.

Back to your request... you wont feel such a big difference in power lose if it´s only 31 to 33", even if it´s n/a diesel, but pulling a trailer without turbo... a very diferent story.

Ulises
AnswerID: 148207

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