D Max Tyres

Submitted: Tuesday, Jul 16, 2013 at 21:31
ThreadID: 103265 Views:7708 Replies:5 FollowUps:12
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Hi Guys,

Is it a problem that I have a tyre placard that says
245/70/R16 on my D max 4x4 and I put 235/70/16 OR
265/70/16 on it?

Pro's & cons maybe?

Thanks
Andrew
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Reply By: Ross M - Tuesday, Jul 16, 2013 at 23:03

Tuesday, Jul 16, 2013 at 23:03
asmithy
I cannot see how going to 235/70/16 is any advantage, it will make the odometer and the speedo around 2% more inaccurate than they are now, also the load rating will be less and if carrying load you may be going close to being overloaded for that tyre size.
This size is -14mm in dia from stock. 735mm dia.

246/75/16 which isn't on your list is + 25mm in dia and same width and increases the road speed 3.3% for the same engine revs. 774mm dia. Not too much increase and still workable if towing a load. The 245/70/16 std is of course the factory matched tyre size at 740mm dia.

The 265/70/16 is + 28m dia and 3.75% over stock size. this will make the engine work harder or the same load and not so good for towing as it is acting like it is half a gear ratio higher.

If yours is an auto the 245/75/16 would be my choice for all round use or retain the original size.

If you are going to climb mountains then the larger wheel helps slightly with clearance. If clearance is not an issue then the OE size tyre or a little bigger won't cause you any appreciable loss of economy.

My second set of wheels are 245/75/16

The 235 width I wouldn't entertain at all.

Hope this helps make a decision.

Ross M
AnswerID: 514903

Follow Up By: olcoolone - Wednesday, Jul 17, 2013 at 08:19

Wednesday, Jul 17, 2013 at 08:19
Why are 245/75/16 tyres OK and 265/70/16 tyres not.....

245/75/16
"Not too much increase and still workable if towing a load"

265/70/16
"this will make the engine work harder or the same load and not so good for towing as it is acting like it is half a gear ratio higher"

245/75/16 have a rolling diameter of 662mm

265/70/16 have a rolling diameter of 659mm

Tyre diameter will knock the performance around more than width.

Have to agree going smaller would decrease the hardening and off no benefit.
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FollowupID: 794063

Follow Up By: Ross M - Wednesday, Jul 17, 2013 at 10:01

Wednesday, Jul 17, 2013 at 10:01
olcoolone
I have std tyres on my Dmax and they are far bigger than what you are quoting as the tyre diameters above.

I think your tyre size chart or calculator has done a big end or the ECU is not computing correctly. Those numbers above are just rubbish.

245/75/16 and 265/70/16 are close but a bit bigger and wider. all takes it's toll on economy though.

Width does definitely knock fuel economy around as does dia increases.
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FollowupID: 794074

Follow Up By: Ross M - Wednesday, Jul 17, 2013 at 10:13

Wednesday, Jul 17, 2013 at 10:13
Alternatively, just work it out with a calculator OR measure the actual tyre and all will be revealed.

265 wide x 70% = 185.5mm x 2 = 371mm add that to a 16" rim
16 x 25.4 = 406.4 + the original tyre 371= 777.4

777.4mm dia is Considerably bigger than the 659mm quoted.
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FollowupID: 794075

Follow Up By: olcoolone - Wednesday, Jul 17, 2013 at 12:43

Wednesday, Jul 17, 2013 at 12:43
From the EO tyre calculator......

Select Wheel/Tyre 1 245/75/16
Select Wheel/Tyre 2 / 265/70/16

Results for your selected Wheel/Tyre 1
Rolling Radius 386.95mm
Circumference 2431.28mm
Diameter 773.9mm

Results for your selected Wheel/Tyre 2
Rolling Radius 388.7mm
Circumference 2442.27mm
Diameter 777.4mm

Differences between Wheel/Tyre 1 & 2
Rolling Radius 1.75mm
Circumference 10.99mm
Diameter 3.5mm

When your speedo reads 100km/hr you're actually at 100.45 km/hr.

Still can't understand why 3.5mm bigger in diameter would be a problem as stated in your post.




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FollowupID: 794083

Follow Up By: Ross M - Wednesday, Jul 17, 2013 at 13:25

Wednesday, Jul 17, 2013 at 13:25
The EO tyre size calculair needs a swift kick up the bum
My std Dmax tyres measure 745mm dia with a few thousand km wear on them.

Also if you take the time, as mentioned, and work it out with new batteries in the calculator you will see what is real.

If you are now saying the dia of what i said are near accurate what does your quote of

"245/75/16 have a rolling diameter of 662mm

265/70/16 have a rolling diameter of 659mm
actually mean?????????????????????



If 246/75/16 is acceptable why go wider and slightly larger again? to 265/70/16.

Ps The rolling diameter of a tyre as quoted by many isn't the real rolling diameter at all. it is always less due to the load.

Radius of a tyre is always larger than the actual rolling radius when in use and it too makes a difference to gearing.

Cheers

Ross M
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FollowupID: 794088

Follow Up By: olcoolone - Wednesday, Jul 17, 2013 at 20:43

Wednesday, Jul 17, 2013 at 20:43
I'm not arguing the diameters...... I will put it in another term..... what I find amusing is you say a Dmax will work quite happily with 245/75/16 that has a rolling circumference of 2431.28mm..... then you go on to say a Dmax will not work well with 265/70/16 that has a rolling circumference of 2442.27mm.

Are you saying a Dmax can not drive tyres 10mm bigger in circumference.

Diameter of tyres have more to do with a common unit to work out hight as a comparison, diameters can alter greatly with weight and air pressure.... the circumference is what matters and you can not alter that.

If diameter played a big part in performance if you ran a tyre a 10psi compared to 45psi you would have a big difference in the speedo reading.

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FollowupID: 794104

Follow Up By: Ross M - Wednesday, Jul 17, 2013 at 22:53

Wednesday, Jul 17, 2013 at 22:53
olcoolone
You don't read what was said. The 265 70 WILL make the engine work harder, just a bit harder than the 245/75. and as said it is harder than the OE tyres

AT no time did I say a Dmax can not drive 10mm bigger tyres. Don't know where you got that from.

Circumference and diameter are locked together and you can't have one without the other. I can't see how you can infer the diameter isn't important but the circumference is. Just not logical.
A tyre of a given dia and circumference, if loaded, will have a working radius less than it's diameter suggests but will still have the same circumference. Tread wear and slip and squirm has to then occur.
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FollowupID: 794110

Follow Up By: olcoolone - Wednesday, Jul 17, 2013 at 23:51

Wednesday, Jul 17, 2013 at 23:51
I got "Dmax can not drive 10mm bigger tyres" the same place as you got "just a bit harder than".

A tyre diameter can vary..... the term "tyre diameter" has nothing to do with PI and is just used as a term that can be related to many tyres to compare overall height.

The diameter vertically of a tyre is constantly changing unlike the horizontal diameter that would be more constant.

If you took the vertical diameter of a tyre when it is inflated and deflated the vertical diameter will vary greatly but if you took a horizontal diameter when inflated and deflated there would be very little difference.

No matter what the diameter is the circumference for a given tyre is non variable.

A diameter is only accurate if it is perfectly round any other shape can not have a diameter but all shapes have a circumference.

A true circle has a diameter.
A true square has diagonals.

But you can convert anything using equivalent diameter...... but for tyres it means very little.... a tyre is a ellipse that has no diameter..... pardon the pun "it will be the focus of discussion another day"
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FollowupID: 794115

Reply By: Sand Man (SA) - Wednesday, Jul 17, 2013 at 07:20

Wednesday, Jul 17, 2013 at 07:20
Andrew,

Why change the tyre size at all?

The 245/70/16 are more than sufficient to take your vehicle anywhere.
They are a more common size and therefore more readily available and at a cheaper price.

If you put the 265's on you should really run a slightly wider rim size to take any advantage from the bigger tyre.

I run 245/70/16's on my Colorado in the newer Bridgestone Dueler 697 LT construction and they are beaut.
I actually downgraded my camper wheels from 265/70/16 so I could match the wheels and tyres and have two interchangeable spares when travelling.
The camper doesn't know any different:-)
I did consider upgrading the vehicle to the 265 size but the change in gearing would have resulted in more trouble than the slight height advantage.

My tip is to stick with the manufacturer's size rating and look for a tyre with a nice looking "aggressive" tread pattern like the Dueler 697 Light Truck.

Bill


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AnswerID: 514908

Follow Up By: Member - Allan L2 - Wednesday, Jul 17, 2013 at 11:43

Wednesday, Jul 17, 2013 at 11:43
Bill,
I would have to agree with you, why change at all?
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FollowupID: 794080

Follow Up By: Member - Phil G (SA) - Wednesday, Jul 17, 2013 at 14:20

Wednesday, Jul 17, 2013 at 14:20
If you're not towing, not loading up and sticking mostly to the bitumen, then I'd agree.

But with 245/75 you get a bit more clearance under the diffs, a bit longer footprint to help in sand, and many brands come with a much higher load index (up to 120) whereas with 245/70 you're struggling to get anything above 113.
I think this matters if you're driving a loaded one ton ute and towing as well - can end up with a heap of weight on the rear tyres.
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FollowupID: 794091

Reply By: Warren B - Wednesday, Jul 17, 2013 at 16:18

Wednesday, Jul 17, 2013 at 16:18
hi guys, have just gone through the same area, Just over 10,000 k's ago I fitted 245/75/16 to the D-max. no real difference around town, in the bush low range is better IMO. HOWEVER !!! kicked it in the arse when we put the van on. Our van comes in at 2750 kgs ( approx. ) in holiday mode and are currently half way into our hols. Max is working harder and fuel consumption lot worse this was something I did't expect not to this extent anyway. The tyres I fitted were GT radials Adventuros 2 and are very happy with them at this stage. Have done a lot of outback roads and Vic high country stuff, but I guess time will tell.

cheers warren
AnswerID: 514920

Follow Up By: Ross M - Wednesday, Jul 17, 2013 at 16:45

Wednesday, Jul 17, 2013 at 16:45
G'day Warren B

I reckon having 2750kg behind a Dmax is pushing it and would be with most utes. The fuel will of course suffer badly, did you do similar /same with the OE tyres to determine if the tyre increase is the cause??

It would have some effect. Probably why it isn't advisable to go to the even bigger size if 265/70/16 where you also have to push a wider tyre.

Not sure why some people up above believe in the Texas syndrome.

Ross M
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FollowupID: 794094

Follow Up By: Warren B - Wednesday, Jul 17, 2013 at 22:23

Wednesday, Jul 17, 2013 at 22:23
Hi Ross M, probably agree with you mate, re: van weight, it is on the upper limit of Kg's but as I drive a Quad dog for a living and have done for years, am prepared to live on the edge a bit. and besides van was ordered when we had L/ cruiser and took so long to build.. anyway long story.
have done the full silver city highway through warri gate to Noccundra to Innaminka, strez track, Oonadat track, flinders rangers etc on OE tyres and got ave 14.5 l/100k's, this trip so far 16 l /100k's

Damm glad Ididn't go for the 265's
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FollowupID: 794109

Reply By: gbc - Wednesday, Jul 17, 2013 at 16:57

Wednesday, Jul 17, 2013 at 16:57
I have had 245/70/16, 245/75/16 and 265/70/16 on the colorado running the same engine.

245/75/16 really is the better choice if you want a mud tyre (simply none available in the oe fitment) They are the tallest and imho the better touring/offroad size.

I went to 265/70/16 to step back to all terrains and still retain some clearance. The tyres (yoko geo atr)are awesome and stick to the road well. The size is a good compromise for a touring tyre and getting some extra clearance.

I don't pay THAT much attention to fuel usage to know which is better or worse. The car still tows well with any of the tyres on.
AnswerID: 514921

Reply By: asmithy - Wednesday, Jul 17, 2013 at 19:04

Wednesday, Jul 17, 2013 at 19:04
Thanks or all the responses guys its really appreciated!

I think I will step up slightly to the 245 75 16.....

Now just to find an appropriate AT tyre for a reasonable price?

thanks guys,
Andrew
AnswerID: 514925

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