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roel



Member Since: 08 Aug 2009
Location: Lelystad
Posts: 2039

Netherlands 2003 Defender 90 Td5 PU Caledonian Blue
Question: What to do to fit 37" tyres.
I have seen a nice set off tyres: Fedima Sirocco 35 10.5 R16. Effectively they are 37".
This is a tall but not to wide tyre, I like that. The tyre is stiff that is the only drawback I think.

What modificaties do I have to make before fitting them on my 90 td5.

I have or are going to do:
Detroit locker in the rear axle
Truetrac in the front axle
I'm going to buy HD rear half shafts.

Currently I have about 1 1/2" lift but hom much do I need?
And what do I need more. Roel

1984 90 2.5 na Diesel - RR V8 (1994-2001)
1997 Camel Trophy Discovery 300TDI (2001-2009)
2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts.
2003 90 Td5 (2009-now)
Post #88178 8th Sep 2011 7:27am
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K9F



Member Since: 12 Nov 2009
Location: Bournemouth
Posts: 9610

United Kingdom 2008 Defender 90 Puma 2.4 XS CSW Stornoway Grey
Hi Roel,

Unfortunately I don't know the answer to your questions but I think I may know a man who does....

Try dropping a 'pm' to 'Big Steve' he likes his wheel tyre combo LARGE by the look of his avatar and he has posted about large tyres somewhere....

Thumbs Up Hope this helps! Thumbs Up

*Update*

Found it....

It's on this thread: http://www.defender2.net/forum/topic2876.html?highlight=tyres

big steve wrote:
ill just chuck the simex on the mach 5s back on for mot but i got anover year yet lol so im not to worried what tyres do you run that wide them mine are kl71s 35x12.50 r15


It may well be to fit them on 16" wheels you will need to consider an inch or two lift on the vehicle, (which I have just re-read your post again and seen you have a lift already). To maintain clearance and to keep the same rolling radius on my vehicle to fit 32 x 11.5 I dropped the size of the wheel from 16" to 15" (I was after a new set of wheels anyway) I note Big Steve also runs on 15". By my reckoning they'll fit ok but may possibly foul on severe articulation, but I am unsure!

Someone will be along that will know for sure! If you go through life with your head in the sand....all people will see is an ar5e!!

Treat every day as if it is your last....one day you will be right!!
Post #88201 8th Sep 2011 10:13am
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BigMike



Member Since: 13 Jul 2010
Location: Lancashire
Posts: 2253

United Kingdom 
Expect issues with diffs and gearbox, half shafts, cv joints. Good luck
Post #88215 8th Sep 2011 1:18pm
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K9F



Member Since: 12 Nov 2009
Location: Bournemouth
Posts: 9610

United Kingdom 2008 Defender 90 Puma 2.4 XS CSW Stornoway Grey
BigMike wrote:
Expect issues with diffs and gearbox, half shafts, cv joints. Good luck


Clearer explanation needed please, otherwise it's just a 'throwaway' comment!!! Why??? Numerous individuals (myself included) have wider/larger tyres fitted and have experienced no issues at all as far as I'm aware! I could be wrong though! Be interested to hear! If you go through life with your head in the sand....all people will see is an ar5e!!

Treat every day as if it is your last....one day you will be right!!
Post #88223 8th Sep 2011 3:42pm
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roel



Member Since: 08 Aug 2009
Location: Lelystad
Posts: 2039

Netherlands 2003 Defender 90 Td5 PU Caledonian Blue
BigMike wrote:
Expect issues with diffs and gearbox, half shafts, cv joints. Good luck


I drive land rovers off-road since 1995 so I have experienced issues. Whistle
I mentioned Detroit locker and a Trutrac so I changed out the most funerable part off the diffs. I also mentioned HD rear halfshafts, I think they should be able to handle it.
The detroit is in the rear axle the truetrac in the fornt so I think the CV joint will get less strain then the rear halfshaft so they might survive or not.
The engine standard not tuned td5 stays the same so why do you expect gearbox problems?

I am considering 4.10 diff ratio.

Like K9F said, I also don't really understand your comment.

Thanks for the good luck anyway. Mr. Green Roel

1984 90 2.5 na Diesel - RR V8 (1994-2001)
1997 Camel Trophy Discovery 300TDI (2001-2009)
2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts.
2003 90 Td5 (2009-now)
Post #88229 8th Sep 2011 3:59pm
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T1G UP



Member Since: 08 Dec 2009
Location: Bath
Posts: 3101

England 2011 Defender 110 Puma 2.4 XS CSW Orkney Grey
diff ratios and maybe an underdrive for off road work.

cv's will be the main concern, upgrades are available but ashcrofts only warrenty to 35" tyres i believe.
Post #88255 8th Sep 2011 6:01pm
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Sonic3d



Member Since: 28 Jan 2008
Location: Ross on Wye
Posts: 1505

United Kingdom 2010 Defender 110 Puma 2.4 XS DCPU Stornoway Grey
37" tyres will put a lot more stress on axles / transmission etc and you will break standard LR parts. If you change the ratio to 4.10 that will help props and gearbox but you will still have a weak link with your front axle only running STD internals. 37" tyres will create a lot more torque due to the extra diameter Thumbs Up
Post #88256 8th Sep 2011 6:03pm
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K9F



Member Since: 12 Nov 2009
Location: Bournemouth
Posts: 9610

United Kingdom 2008 Defender 90 Puma 2.4 XS CSW Stornoway Grey
Sonic3d wrote:
37" tyres will create a lot more torque due to the extra diameter Thumbs Up


Am I correct in assuming if you reduce your rim size accordingly to maintain as close as possible to the original rolling radius the stresses and strains are nulluified with exception of the ones caused by the extra width? If you go through life with your head in the sand....all people will see is an ar5e!!

Treat every day as if it is your last....one day you will be right!!
Post #88261 8th Sep 2011 6:19pm
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Sonic3d



Member Since: 28 Jan 2008
Location: Ross on Wye
Posts: 1505

United Kingdom 2010 Defender 110 Puma 2.4 XS DCPU Stornoway Grey
Yes Thumbs Up
Post #88266 8th Sep 2011 6:29pm
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roel



Member Since: 08 Aug 2009
Location: Lelystad
Posts: 2039

Netherlands 2003 Defender 90 Td5 PU Caledonian Blue
37" is 19% more diameter and so torque then my current 235 85 16 BFG MT's that I bought for my Camel Disco. For the Disco they were nice for my 90 not big enough.
so a 37" tyre is 19% and torque than standard.
35" is about 13% more.

So what is acceptable and what not.
Maybe I have to upgrade the CV joints too.

If I change the diffs to 4.1's that is a reduction of about 16% so for the gearbox and transfer box it is only an increase of 3%. That shouldn't be a problem I think.

SO the danger will be CV's and Half Shafts.

Other question: How much lift do I need from standard for the 37".
From 31" to 37" is 6" so lift needed is 3". Is my thinking correct? Roel

1984 90 2.5 na Diesel - RR V8 (1994-2001)
1997 Camel Trophy Discovery 300TDI (2001-2009)
2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts.
2003 90 Td5 (2009-now)
Post #88278 8th Sep 2011 8:41pm
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big steve



Member Since: 24 Dec 2009
Location: hertfordshire
Posts: 2456

United Kingdom 2015 Defender 90 Puma 2.2 HT Montalcino Red
How we doing guys well I'm running 35 x 11.5 simex on my truck with an ome lift with no proves at all slight nip of the arches and job done
Also no problems with drive train arbs all round with ashcrofts shafts and cvs every thing runs fine too
Ok blew a front diff up before I got the arb but thy was my own fault

I wud say u need at least a 3 inch lif for 37s

Regards steve 2015 2.2 tdci hardtop xs
3.2 conversion DONE 238bhp and 707nm torque and thats just the start ;-P
hybrid turbo in build -done ready to fit
ashcroft atb in transfer box
6 speed auto in build
Post #88284 8th Sep 2011 10:08pm
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roel



Member Since: 08 Aug 2009
Location: Lelystad
Posts: 2039

Netherlands 2003 Defender 90 Td5 PU Caledonian Blue
Did you measure your tyres? Because the fedima's are 35 x 10.5 R 16 but when measured they are 37" Whistle Roel

1984 90 2.5 na Diesel - RR V8 (1994-2001)
1997 Camel Trophy Discovery 300TDI (2001-2009)
2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts.
2003 90 Td5 (2009-now)
Post #88301 9th Sep 2011 8:24am
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McS



Member Since: 05 Oct 2009
Location: Banbury
Posts: 686

Scotland 
I run 37" Boggers on my competition car. Since you're looking at the Fedima's I'm assuming you do a fair amount of off road work, so I'll base my recommendations on that.

As has been suggested, your half shafts and CV's will be vulnerable, not only due to the size of the tyre but also because of how aggressive it is. If your budget is a limiting factor, I would look to upgrade the front half shafts first, followed by the CV's and then the rear shafts. HD drive flanges would be worthwhile too. There are a number of options available of all of these (ashcroft, KAM, GKN, Rovertraks, Longfield etc) so it's worth having a good look around the market to see what option suits you best.

The amount of lift you require will depend entirely on how much flex you want the car to have. To be useable you will need a 2" lift. To gain more upward travel, you will obviously need more. Personally I'm not into huge amounts of flex so I run OME 762 and 764 springs with relocation cones, +5" terrafirma remote reservoir shocks and extended bump stops. This provides me ample suspension travel and stops the 37's from anihilating the inside of the rear tub!

Your gearbox on that vehicle will be absolutely fine, unless you drive like a complete lunatic in which case your tyre choice will have very little bearing on how quickly your gbox goes bang!

I would definetly recommend changing the diff ratio to 4.11. This makes things a lot more controlled off road and also provides you with stronger diffs (more surface area contact between CW & P).

I hope that helps, glad to offer any more advice I can.

Regards,

Ross The Scotia Winch Challenge
Post #88320 9th Sep 2011 10:52am
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BigMike



Member Since: 13 Jul 2010
Location: Lancashire
Posts: 2253

United Kingdom 
Ok, I see my "throwaway comment" has already been explained by others Thumbs Up
Post #88322 9th Sep 2011 10:56am
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millepet



Member Since: 01 Apr 2013
Location: Wijnendale
Posts: 33

Belgium 2009 Defender 110 Puma 2.4 SW Orkney Grey
Did you fit the wheels, and what kind of modifications? I have 17x9 beadlock

Click image to enlarge

rims for 37x12.5R17 BF Mud Terrains to have more ground clearance for my trip to Iceland next summer. I was there 2 summers ago, and had water up to the top of the bonnet during river crossings.I need more ground clearance.I do not intend competition style off roading.
Post #604916 26th Feb 2017 10:55am
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