32s or 33s?

[Jeff]

I am thinking of getting some 32" Mud Terrains, but should I be getting 33"s?
They will be my second set only on for play, not every day. My Defender is a standard TDi, so will 33s kill the performance too much? Are there other advantages or disadvantages to either size?

Jeff

:rocket:

[rick130]

A Tdi Defender is fine with 33's.
Been using them for years (on my third set of 255/85's) as a daily driver and the 130 is grossing at 3 tonnes these days.

Admittedly the pump has been turned for a few years now too, which does help.

[georgesadlik]

I am thinking of getting some 32" Mud Terrains, but should I be getting 33"s?
They will be my second set only on for play, not every day. My Defender is a standard TDi, so will 33s kill the performance too much? Are there other advantages or disadvantages to either size?

Jeff

:rocket:

33's Jeff. Mainly because you know you you want them. With the 32's you'll always be wondering - what if? :wasntme: Plus they'll roll quite well on the Defender i think.

Cheers

George

[isuzutoo-eh]

I was punting around Newnes Plateau with another County owner, both packing near-new bighorns, his 32" mine 33". Came upon a particularly well known boghole. I drove through. He didn't. That extra half inch under the Salisbury plough can make a difference!

[lambrover]

I second the 33's, they also correct the speedo. any thing you can get under the rear diff is a bonus.

[rick130]

I was punting around Newnes Plateau with another County owner, both packing near-new bighorns, his 32" mine 33". Came upon a particularly well known boghole. I drove through. He didn't. That extra half inch under the Salisbury plough can make a difference!

It isn't hard to take near 3/4" off the Sals either without affecting its integrity.

[LowRanger]

Jeff
Buy the 255/85/16's and you won't look back.Otherwise you will be out one day and become hung up on a diff and be cursing the day that you didn't buy bigger tyres.

You will probably find that your speedo will be more accurate with the bigger tyres and that the vehicle will run at a more relaxed engine speed when cruising,which will make it more pleasant to drive for longer.

Cant really think of too many reasons to keep the 235's,but I am sure some of the "purists" will think of something.

JUST DO IT:twisted:

[rick130]

Jeff
Buy the 255/85/16's and you won't look back.Otherwise you will be out one day and become hung up on a diff and be cursing the day that you didn't buy bigger tyres.

You will probably find that your speedo will be more accurate with the bigger tyres and that the vehicle will run at a more relaxed engine speed when cruising,which will make it more pleasant to drive for longer.

Cant really think of too many reasons to keep the 235's,but I am sure some of the "purists" will think of something.

JUST DO IT:twisted:

I reckon the 255/85's make 4th and 3rd gears better for on-road use too.

[uninformed]

Im no purist, and would like to run 255/85R16s but I cant bring myself to run them on my truck....I need all the torque I can get :(

[rick130]

Install a pyro and tickle up the pump, problem solved :p

[uninformed]

Install a pyro and tickle up the pump, problem solved :p

got the pyro, got the pump and cc's but dont want the resulting "bang" :eek:

[rick130]

got the pyro, got the pump and cc's but dont want the resulting "bang" :eek:


Just 'cause it's cost a few little $ in engine repairs/replacements and you get a little gun shy :D

[lambrover]

got the pyro, got the pump and cc's but dont want the resulting "bang" :eek:

Did you adjust the boost as well, if you adjust the pump with out adjusting boost you are robbing your self of power gains and you will be running higher EGT's. Remember boost won't hurt the engine but high EGT's do.

[rick130]

Did you adjust the boost as well, if you adjust the pump with out adjusting boost you are robbing your self of power gains and you will be running higher EGT's. Remember boost won't hurt the engine but high EGT's do.

He's running an HS2.8 TGV, boost isn't an issue ;)

[lambrover]

He's running an HS2.8 TGV, boost isn't an issue ;)

nice set up :)

[butundede]

Do the 255 85 16's have any effect on the durability of the driveline?

[rick130]

Do the 255 85 16's have any effect on the durability of the driveline?

Larger always puts greater load on things but the CV's are most at risk so try and avoid full nelly, low/low on full lock.

[Jeff]

So, having decided on 33s, which width, 10.5 or 12.5?

Jeff

:rocket:

[LowRanger]

So, having decided on 33s, which width, 10.5 or 12.5?

Jeff

:rocket:


Jeff

Unless you have extra wide flares and extra offset wheels,12.5" tyres will be too wide.
The size you should look at is 255/85/16

[Jeff]

Jeff

Unless you have extra wide flares and extra offset wheels,12.5" tyres will be too wide.
The size you should look at is 255/85/16

Oops, I just bought some 33-12.5/15s, I have the extra off set wheels and the extra wide flares will come soon.

Jeff

:rocket:

[LowRanger]

Oops, I just bought some 33-12.5/15s, I have the extra off set wheels and the extra wide flares will come soon.

Jeff

:rocket:

Jeff

You left out one very important piece of information,when you were asking for recommendations:oYou forgot to mention that you were after 15" tyres;)

[SG1]

Did you adjust the boost as well, if you adjust the pump with out adjusting boost you are robbing your self of power gains and you will be running higher EGT's. Remember boost won't hurt the engine but high EGT's do.

I need some help: Lambrover (or any other who knows): how do I increase the boost in my 2.8 TGV engine? There are lots of explanatons on this forum and others on how to tweak the pump (which I have already done, moderately), but what about increasing boost? Can it be done at home? Is ther any póst on this that you could lead me to?

Thanks!
Stgo

[rick130]

Santiago, AFAIK you can't ?

That turbo is putting out maximum boost at revs ?

I've read anything from 18-20psi, much more than a stock 300Tdi turbo.

[DEFENDERZOOK]

if it helps with anything......i am currently running 33 12.5 x15 on my 03 fender....only mod is a 2 inch spring lift.......

the taller sidewall gives a little more shake and wobble as can be expected......and you also notice a bit more tyre roll on hard cornering.....
this is compared to the factory 235 85R16.......but i like the rolling diameter and don't want to go back to the 32s.......
the speedo is now almost accurate......its about 15metres out over 5kms.....

BUT.....my backing plate just touches the rim on some corners......which is a very simple 5 minute fix with some sandpaper....or a file......
an angle grinder will take longer by the time i connect up extension cords and run them out to the car......

you are more than welcome to come and have a look/drive of mine if you like.....im in illawong.....near menai......

[Jeff]

if it helps with anything......i am currently running 33 12.5 x15 on my 03 fender....only mod is a 2 inch spring lift.......

the taller sidewall gives a little more shake and wobble as can be expected......and you also notice a bit more tyre roll on hard cornering.....
this is compared to the factory 235 85R16.......but i like the rolling diameter and don't want to go back to the 32s.......

What pressure do you run on road?

Jeff

:rocket:

[DEFENDERZOOK]

i was running 40psi in the factory rubber....general grabbers.....

but in these I'm running only 32......as the maximum pressure is only 36psi.....
these are very old tyres.....prob 20 years old......?

[newhue]

Been reading about highway and clearance benefits regarding 33" tyres, but what about low range capability.

3 of us all driving Defers were just down Cooma in some pretty hilly and slippery tracks.
The Tdi had 33" and a 30% reduction gear which the owner feels brings the car back to standard gearing with the tyres on.
The td5 has stock 32", and my puma has stock 31".

The TD5 and puma want to go to 33" next round, but wonder if we could loose some of the slow landy crawl. As we drove these hills in 2nd low, we would work these cars between 1300rpm and 2200rpm over the tracks. Virtually no wheel spin was present and they predictably crawled there way up, nice and safe.

I'm not keen to cough up for a reduction gear in the puma to keep low gear talk like standard, and not keen either to climb hills at 1690 and 2860rpm.

thoughts and experiences please

[Jeff]

Been reading about highway and clearance benefits regarding 33" tyres, but what about low range capability.

3 of us all driving Defers were just down Cooma in some pretty hilly and slippery tracks.
The Tdi had 33" and a 30% reduction gear which the owner feels brings the car back to standard gearing with the tyres on.
The td5 has stock 32", and my puma has stock 31".

The TD5 and puma want to go to 33" next round, but wonder if we could loose some of the slow landy crawl. As we drove these hills in 2nd low, we would work these cars between 1300rpm and 2200rpm over the tracks. Virtually no wheel spin was present and they predictably crawled there way up, nice and safe.

I'm not keen to cough up for a reduction gear in the puma to keep low gear talk like standard, and not keen either to climb hills at 1690 and 2860rpm.

thoughts and experiences please

Mine was not noticeably different to the 32" normal tyres, but I don't have a tacho and the Rover was empty. Might be different if filled up with two weeks food and camping gear.

Jeff

:rocket:

[PAT303]

I don't think bigger tyres would hurt the Puma at all,as you'd know 1st low is lower than anything this side of a tractor. Pat

[Drover]

The td5 has stock 32", and my puma has stock 31".

PUMA's have 235/85/16 or 32's.

I am about to get new wheels and tyres and will be going to 33's (285/75/16).

[newhue]

PUMA's have 235/85/16 or 32's.

I am about to get new wheels and tyres and will be going to 33's (285/75/16).

ooo you wagon drivers, us utes or Defers without alloys have 7.5x16, which = 31"

who's 33 are you going with.

[newhue]

I don't think bigger tyres would hurt the Puma at all,as you'd know 1st low is lower than anything this side of a tractor. Pat

yeh 1st is out there on it's own, but travelling at 4klm for 50klm is no good either. Second is an awesome gear for crawling along in low.

It seemed to all of us LR have specked there vehicles very closely over the years regarding power, talk, and gear ratios. I presume since they all run the same transfer box this is partly why.
A puma donk for all it engineering and latest fuel delivery is no more economical, or not much more power than a TD5, or TDi.
In fact the puma was the one using more fuel than the others, maybe a bit heavier vehicle, maybe the air con on all the time.

[Didge]

Jason, interesting comment on 7.5R16's = 31". I have a set of 7.5R16's and 31x10.5R15's and the 7.5's are about 1.5 - 2" bigger in diameter than the 31". But that's just measuring them laying on the driveway.
Question guys - how do the 33's affect fuel economy compared to standard diameters? I've read that wider tyres also reduce economy quite a bit. Also, forgive my ignorance but what's the pyro?
cheers Gerald

[marting]

It is hard to tell about the fuel economy because the speedo changes when you up in tyre size which throws out the distance travelled per tank. I havn't noticed any dramatic change though. But, just going by experience, in a standard tdi, I found I would be back to 4th earlier on some hills, but the overall improvement by going to 33's for outweighs this. As someone posted earlier they bring the engine rpm at 95 - 100km/hr down making for a much more enjoyable time on the highway.
I did however fit the maxi-drive 30% reduction gearset into the transfer case because I didn't want to lose any low range and the transfer case needed overhauling anyway. First low would seem to be on par with the Puma 130.
Cheers, Martin

[Sitec]

Drover... Defer with 285's pictured...

[Furka]

Sorry, but I think the 7,50x16" are 32" . The 31" are the 7.00x16".

[Drover]

who's 33 are you going with.

Leaning toward Mickey Thompson Baja MTZ's but BFG KM2's are also under consideration.

I have got quotes for KM2's - $350 ad Baja MTZ's - $359.

Price is much the same, any opinions on these brands/tyres ?

[isuzurover]

ooo you wagon drivers, us utes or Defers without alloys have 7.5x16, which = 31"

who's 33 are you going with.

Despite the maths, 7.50s are 32".

[rick130]

Despite the maths, 7.50s are 32".

It can also depend on the manufacturer.

When I bought the 130 it had half worn XZL's on the back and near new 235/85 Bridgey MT's on the front and from what I can remember there was something like a 3/4" difference in OD.
I did measure it at the time but it was ten years ago now.

The t/case fluid was a lovely colour and odour too :o

[MLD]

Drover - if you go with the 285/75R16 you might not get them on the 16 x 7" rim. I was told by Bob Jane that the 255/85R16's are just on perfect for the 7" rim and i was told by others that the 265 is the legal limit for a 7" rim. Worth asking around before you part with your cash. Be a shame if you had to change from your SVX rims.

I have the BFG KM2's in 255/85 and very happy with them. Noisy at 60 to 80km/h but after that the defender's sound deadening supersedes the tyre noise. It's an unconducted orchestra at 100km/h.

To the others that enquired about the 33". Mine corrected my speedo at 100km/h. With 235/85's it was 5km/h inaccurate. On my maths the increased circumference reduced my RPM at 100km/h by about 425 rpm. It has made a considerable difference to gearbox and driveline whine at highway speed. (math's wasn't my strong point, preferring the fairer sex and sport at school).

The 255/85 BFG KM2's have a marginally larger rolling diameter to the comparable sized Maaxis bighorns. The Bighorns are significantly cheaper. The 255/85's are an unusual size and are a low volume import. Expect to pay a premium over the 285/75's. Also if you do a lot of touring be prepared to wait days for replacement tyres in regional towns. They are not likely to be a stocked item.

I upgraded my ECU map soon after fitting the 33's so I can't remember if it affected my acceleration. The remapping has had a significant effect on acceleration at highway speeds. Around town my grandmother has a faster turn of speed than the defender. It would be harsh to blame the larger rubber.

As for fuel consumption. On the standard 235/85's I ran just on 10 ltr/100km combined. With the 255/85's it increased to 11.2 ltr/100km combined. I did jump from 235/85 road orientated tyres to 255/85 mud tyres. Both factors no doubt contribute to the increase in fuel consumption. Fully loaded with camping equipment i get 12 to 12.5 ltr/100kms on the black top and about 14 to 14.5 ltr/100km on the tracks.

as for the 7.0 v's 7.5" discussion. my understanding of the maths is 7.5 x 16 = 31" ie 7.5 x 2 + 16. 7.0 x 16 = 30". I understand that there was some loose sizing standards between manufacturers, but the rational of the maths was consistent.

Pyro - measures exhaust gas temperature. Over fuelling in a diesel causes an increase in combustion chamber temp indicated by an increase in exhaust gas temp. High exhaust gas temps is an indicator that you are trying to kill your engine prematurely. Easing off the right foot or changing gear if labouring in too high a gear will usually reduce the EGT.

cheers MLD

[rick130]

[snip]

The 255/85 BFG KM2's have a marginally larger rolling diameter to the comparable sized Maaxis bighorns. The Bighorns are significantly cheaper.

[snip]

cheers MLD

I think you might find it's the other way around on the charts, (from memory about 5mm taller for the 762) but probably well within manufacturing tolerances in the real world.

When I measured up my 762's when new and inflated @ 30psi on 6.5" rims they measured pretty dead on the designated diameter (2650mm = 844mm unloaded diameter)

[MLD]

Rick130 - there you go, my lesson for the day. BFG's Aust and US website doesn't quote rolling circumference.

5mm could be evened out by a weekend crawling up rocks.http://www.aulro.com/afvb/images/smilies/ohmy.gif

cheers MLD

[rick130]

Circumference is the easiest way to measure diameter if you have a tape, just divide by pi.

[Drover]

Drover - if you go with the 285/75R16 you might not get them on the 16 x 7" rim. Be a shame if you had to change from your SVX rims.cheers MLD

Thanks MLD,

Planning on getting a set of 6 black 16 x 8 steels wheels at the same time.

Going to use them just for trips and the SVX wheel and GG's for road use and around town.

I do agree that a 265 is max width on a 7" rim.

Cheers

[newhue]

Leaning toward Mickey Thompson Baja MTZ's but BFG KM2's are also under consideration.

I have got quotes for KM2's - $350 ad Baja MTZ's - $359.

Price is much the same, any opinions on these brands/tyres ?

The only feed back I have is a mate has just done a lap of Aus towing a trailer with MT MTZ's, he just replaced them with the same.
Half way round he was talking up BFG KM2's as many people had them and they seemed to be holding up well from his observations. This is surprising as his not big on BFG.
I have driven a lot with a Defer mate who runs Maxxis Bighorns, they have done all my XZL's have, but haven't worn like mine, and are far cheaper.
that's all I know.

PS, I use the Explore Aus tyre calculator to work out tyre size.

[Freestyler]

Hi Jeff I have been running BFG 33 x 10.5's Muddies on my truck over 10 years now. Bit taller but not too wide I have found them to be a good all round tyre. Ive been on the beach, in the desert, through mud and over rocks. I run them in the bush at 20psi and have very little issues. OK milliage and very few flat tyres. I have a V8 County 4.4 Ltr EFI so I have horse power to burn but I did notice a difference with the old 7.50 16's. Looks realy stupid now after the 33's for so long and I wont be going back.
Tim

[86mud]

Hi all

I am currently looking at getting a set of Dynamic 16 x 8 with 25mm offset rims and a set of Mickey Thompson MTZ's in 285/75/16's for my 1998 300TDi 130.

I have always had BFG's either mud terrains (on my previous Range Rover 35") and currently all terrains on the 130 (standard 235/85 16) . So why the change to MTZ's? I am not keen on the BFG KM2 pattern. I prefer the old style BFG mud terrain pattern but it is now unavailable (be happy to be told different!)

The only issue at the moment? I have only 40mm clearance between the roof of the truck and my garage roller door and I hope the change in size up to 285's means I can still fit the truck into the garage.

And....I will be looking at swapping bonnets - one without the spare wheel carrier as there is no way I will be putting a 285/75 tyre on the bonnet!

Cheers
Andrew