Tyre Sizes and outcomes...

Submitted: Sunday, Apr 08, 2007 at 23:20
ThreadID: 44114 Views:3190 Replies:7 FollowUps:2
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Hi everyone,

I have finally decided that I am going to go with Cooper Tyres, but what I am seeking is the pros and cons on tyre sizes.

Land Rover Disco
1997 S1 300Tdi 2.5lt

My tyre sizes are:

Factory fitted: 235/70/R16
Currently fitted: 225/75/R16 LT BFG MT
Possible fitting: 245/75/R16 LT Cooper ST's

What I need to know is there anything I should know as I am hearing heaps of opinions and not facts.
What happens when I put bigger tyres on?
Do I go bigger, back to factory size or stay with the current smaller?
Is my clutch go to work harder with bigger tyres?
Should I use LT construction or standard?

Just to name a few!!!

To save typing if anyone knows a website that has all the information it would be greatly appreciated.

The smaller tyres were put on by the previous owner to see if it would reduce road noise.

I have decided to purchase Cooper ST's as I don't do heaps of 4WDriving, but if someone thinks that STT's are a better buy then let me know.

Cheers Dave Huxtable
Wodonga Vic 3690

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Reply By: Truckster (Vic) - Sunday, Apr 08, 2007 at 23:33

Sunday, Apr 08, 2007 at 23:33
>> What happens when I put bigger tyres on?
Your gearing changes, your brakes dont work as good, your speedo goes out, you may become unroadworthy, on some cars, depending on how big you go, your clutch may suffer to get your truck moving at lights, but every car is different, your spare tire maynot fit properly in the space provided (It happens on some makes/models) etc.

>> Do I go bigger, back to factory size or stay with the current smaller?
If you dont do heaps of 4wding, why do you need bigger?

>> Is my clutch go to work harder with bigger tyres?
more rubber to turn, so yes.

>> Should I use LT construction or standard?
AnswerID: 232314

Reply By: Hux1405 - Sunday, Apr 08, 2007 at 23:41

Sunday, Apr 08, 2007 at 23:41
Thanks for the reply...

I was going to go up to the bigger 245 because it comes in the LT construction(same as the 225), whereas the 235 is just standard...

I cant understand why they don't make them all the same :)

Thanks for your input


Dave Huxtable
AnswerID: 232315

Reply By: marcus - Monday, Apr 09, 2007 at 10:03

Monday, Apr 09, 2007 at 10:03
Hi Dave,
The down side of putting bigger rubber on is as Truckster says and perhaps the main plus is having a taller vehicle and a large rolling radius wnen off road.
My discovery TD5 actually drives better on the standard 235/70/R16 as the gearing is how the engineers designed it.When i fit the steel rims with the MTR's at 245/75/R16 i find that i lose a bit of economy,i lose a bit of puff on the long hills and i have to cruise at 96km/hr to achieve the 100 or risk a possible photo.I would say if you don't do a lot of off road just stick to the standard 235/70/R16 for a better all round drive.
Cheers Mark
AnswerID: 232343

Reply By: Member - Michael G (QLD) - Monday, Apr 09, 2007 at 10:38

Monday, Apr 09, 2007 at 10:38
Hi Dave ,
I have a 2000 series 2 Disco and I run 265/75/R16 on steel rims.
When you go to bigger tyres you do have some changes as has been said.
What you have to deceide is what you will be doing with the vehicle.
Bigger tyres give you more height so therefore more clearence under the
The downside is your gearing changes slightly.
I have put a chip in mine an also a 3"exhaust system.

AnswerID: 232348

Reply By: Member - Des - Monday, Apr 09, 2007 at 11:30

Monday, Apr 09, 2007 at 11:30
Sorry to raise another question, but if you don't do heaps of 4WDing, mightn't the Cooper ATRs be a better option than STs? Would be much quieter, and handle better on wet bitumen. One of the striking results in the 4WD Monthly AT tyres test last year was the big difference in braking distance on wet bitumen between aggressive ATs like Cooper ST, BFG & Dick Cepek compared with less aggressive AT tyres like Pirelli Scorpion AT and Bridgestone Dueller D694. Cooper Discoverer ATRs would be quite comparable with the latter two.

Certainly if you don't go off road a lot, the STTs would seem to be overkill.
AnswerID: 232362

Follow Up By: Muddy doe (SA) - Monday, Apr 09, 2007 at 17:42

Monday, Apr 09, 2007 at 17:42
Having done 40,000 km with the Cooper ATR's on my Prado I will second Des's thoughts.

They also look like they will do another 30 to 40,000 pretty easily as well. They are the LT construction. I have a different size to what you want (Prado run 17" rims) but they probably make them in the sizes you want and they are a great allround tyre.

FollowupID: 493278

Follow Up By: Member - Bucky (VIC) - Tuesday, Apr 10, 2007 at 06:32

Tuesday, Apr 10, 2007 at 06:32
G day Muddy

Done 75k on my Cooper ATR's now, on my Navara, and got heaps left in them.
And in that, done 2 desert trips too !
No doubt they are a gr8 tyre, but they seem to be getting harder. ( more bounce )
Could be the same roads getting harder ( hehehe )
I run 27-28 in the back and 31-32 in the front,
Do my own rotation, every 5k, and every other rotation is a criss cross.
Cheers Mate

ps ,,, how's it all going too ?
FollowupID: 493373

Reply By: keepingitreal - Monday, Apr 09, 2007 at 16:58

Monday, Apr 09, 2007 at 16:58
someone on here gave me this website: http://www.1010tires.com/, very handy info on there. I my self have a 100 series with 255/85R16. A lot taller. Lose accceleration on my old girl, but better ride and no lurching sideways as nice and narrow. Have to watch the speedo though as they are about 6% faster. Hope this website helps. Cheers
AnswerID: 232404

Reply By: pt_nomad - Monday, Apr 09, 2007 at 18:26

Monday, Apr 09, 2007 at 18:26
I have 245/75/R16 on an s1 discovery. My tires are good year wrangler MTR's.
I went with this size for off road abilty and higher load rating with the size (in most tyre designs). I found I was getting an excessive number of punctures on the smaller tyres as we we pushing the vehicels load limit (family of 5), the higher load rating tyres have resolved this problem.

The larger size will require at least a 2" lift. The rear section of the read guard did foul on the tyres. Rather than an expensive panel re-shaping, if you undo the panel locating bolt under the rear quater panels and the drill another hole 12mm from the original the guard wil flex out with out any damage and create sufficient clearance for the tyres. It it easily reversed if smaller tyres are fitted.

The larger tyres do use more fuel, esp as mine are a mud pattern.
V. happy with the bigger tyres for my off road set. I always moter around town / tow the boat on stock size allTerrains. I am very unimpresed with stock size BFG AT's for durability off road.

You can check the effect on diameter @ http://www.lrc.org.au/4wdstuff/tyre.xls

AnswerID: 232417

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