235/85/16 vs 245/75/16

[Rezley]

Hi All,

So I've had standard size tyres 235/70/16s, 225/75/16's and now 235/85/16s on my Disco.

Shes nearly read for new boots.

Considering 245/75/16s this time but been happy with 235/85/16's so tempted to stick with them.

Obviously Ill retain better clearance with 235's but possibly better on road handling with a 245?

Is there anyone whom has run both over the years and has useful feedback on your thoughts for each case 235/85 vs 245/75? on road and off?

Thanks,
Rez

[steelo]

How were the taller boots off & on road? Oh & what were they, i.e. muddies, A/T's? did you need the "camel cut"? :confused:
Just asking as am tempted to get taller 235's, thanks :D

[DiscoMick]

I went from 235/70/16 ATs to 245/75/16 MTRs. Had to adjust the steering to stop them rubbing by limiting how far the wheels could turn, which was an easy job once I figured out how to do it.
I've been told the better size for a D1 is 245/70/16. I think that was actually fitted to some American D1s, but I could be wrong.
My D1 has a 50mm lift, but the wheel arches have not been trimmed.
You can certainly feel that the vehicle has larger, wider tyres and is sitting higher. On the road the larger MTRs are noisier than the smaller BFG ATs were. Off road, its a big improvement, so it's a trade-off.
Hope that helps.

[Distortion]

I've had both on my disco and the preference is for 245/75/16, I only tested the 235/85/16 for a couple weeks when I got my 110

I have a 300tdi manual and found the extra height of the 235/85/r16 too sluggish to the point where it was annoying taking off.

I've driven a v8 auto and that copped with the extra height much better and I think a 300tdi auto would be ok as well

I've got a camel cut and a sagged +2 lift

[loanrangie]

245/70's should have been the standard size as they are near enough perfect for a D1, i prefer 265/70's on my tdi auto bar the speedo correction required.

[gazby]

On our '98 Tdi with 2" suspension lift we have 245/70 Bridgestone A/T's, nearly due for new boots, still working through what to buy but love the look of BFG M/T.
Have had no clearance issues in some pretty articulated suspension situations.
Engine performance is still ok with presumably moderate rolling diameter increase.

[finallyrangie]

I have 245/75's on at the moment, which put the speedo spot on, and don't seem to make the take off too painfull with a manual gearbox, I am actually tempted to try 235/85's next time, think the narrower profile might be better.

good question, keeping an eye on peoples replies

[libertyts]

I like my 245/75/16's on the disco. Little extra height and just a little wider which I prefer. However it puts my speedo out about 5ish %. Not a huge problem, just means I have to remember to take that into account when calculating my fuel economy figures.

Also, as far as I'm aware, there are more options in tyres for the 245's and usually a little easier to source.

Chris

[loanrangie]

I like my 245/75/16's on the disco. Little extra height and just a little wider which I prefer. However it puts my speedo out about 5ish %. Not a huge problem, just means I have to remember to take that into account when calculating my fuel economy figures.

Also, as far as I'm aware, there are more options in tyres for the 245's and usually a little easier to source.

Chris

Are you sure its out, most here with 245/70 or 245/75 find that the speedo is now spot on. When i have the 265/70's on its about 5% under reading.

[Foxspell]

Hi Chris,
I think you are confusing your speedometer with your odometer.
I find that on original tyres Speedometer is approx 7% optimistic however Odometer is accurate.
Your tyres would change this by approx 5%, hence your Speedometer would now be approx 2% optimistic however your your Odometer would under read by approx 5%. It is this 5% you would need to take into account when calculating mileage even though your speedo is pretty close to the mark.
I hope this makes sense.

Lee

[steelo]

I find that with my standard 235/70/16's when my speedo is showing 100kph the GPS is reading 96kph :D

[libertyts]

Hi Chris,
I think you are confusing your speedometer with your odometer.
I find that on original tyres Speedometer is approx 7% optimistic however Odometer is accurate.
Your tyres would change this by approx 5%, hence your Speedometer would now be approx 2% optimistic however your your Odometer would under read by approx 5%. It is this 5% you would need to take into account when calculating mileage even though your speedo is pretty close to the mark.
I hope this makes sense.

Lee

I understand what you are saying, however after testing with several GPS I have found my speedo and odo to be fairly close if not the same and both being around 5% out. Not exactly, but close enough.

As far as I understood it, the speedo and odo should show no real difference in regards to distance etc as they are based off of the same "signal". I could be wrong, but that is the way I understood it at least. I just don't see why LR would produce two different "signals" for essentially the same thing. The only difference between them is one is over a set time (per hour) and one is just a total traveled distance.

If anyone has any corrections I would be happy to hear them. Oh and sorry for the thread hijacking!

Chris

[gazby]

Isn't it just plain physics, the standard fitted tyres to a D1 was either the 215/16 or 235/70/16, at least they are the only two sizes that are mentioned in my owners manual and on the tyre placard on the drivers door.
A 235/70 has a rolling diameter (when new) of 735 millimetres, whereas the 245/75 is 774 millimetres and thus covers roughly 121 millimetres per rev more than the 235/70.
The speedometer by law has to have a reasonable degree of accuracy, so the 5% innacuracy of the speedometer with the bigger tyre is pretty right, about 52 metres further in the registered kilometre.
Maybe these days with the "Rozzers" having all the hi-tech gear in tow to nail you for drifting over the speed limit that could be a problem, but as said by others, just make an allowance for it or treat your GPS like the American Express Card, and "don't go anywhere without it".
Please feel free to correct my shoddy mathematics.

[SouthOz]

As for speedo and odometer reading the same, my bike speedo is around 8% out whereas the odometer is spot on according to my GPS. Both get their signal from the same sender. Not saying that my GPS is 100% but just that there is variation between the speedo and odometer.

Dave

[Rezley]

Thanks for the replies, speedo does not worry me as its out further with 235/85 than 245/75 so I'm already used to it.

Take off is also ok as its a manual V8.

From what I've read I think I'll stick with 235/85s

Steelo,
They have been good offroad, currently a BFG MT, better than anything Ive had on it before offroad but onroad is pretty woeful, especially in the wet so Im considering an aggressive A/T or something similar.

[Rezley]

Quick update, should be getting 235/85/16 GoodYear Duratracs in next week or two.

Its about the most aggressive AT I could find so hoping it will serve my purposes better than an all out MT.

Cheers,
Rez