265/65/17 to 265/70/17 how much difference?

[timmo23 Lurker Find all posts View Profile Close timmo23]

Hi I have an 07 auto that needs some new feet and I am looking at going up a size in tyres mainly to fill the gaurds up a bit as it has a 2in lift. As most of my use is hiway I don't want to lose too much in power and economy and am wondering if anyone has done this tyre size change and can give me some idea how much difference it will make.

[Guest Close Guest]

It will make a huge difference to your economy. Mine went from around 12 L per 100 to around 16 per 100 on Hiway (AVG) my economy around town is average 15-17 now.
Mind you this is with the speedo error, so it may be slightly under this.

Your speedo will most likely have a 4% error too.

Some 70 series are not as big, the Mickey MTZ seems to be one of the larger by about 8mm diameter.

[Bushbasher Out of control poster! Find all posts View Profile Close Bushbasher]

This issue keeps coming up. I have 265/70 BFGs on my rig. There is no noticable increase in consumption. She will do 10l at 100, 11 at 110, 12 at 120, etc. Mine would do better than 16 towing the camper trailer. This is with ARB bar and 2 inch lift.

The tyres have actually made the speedo 100 accurate. I have confirmed this with Decatur on board mobile radar and GPS and Tru Speed laser, all certified for speed measurement. The 265/65 will have your speedo reading 4 - 6km faster than true speed.

[Auss15 Junior Member Find all posts View Profile Close Auss15]

This is a handy page that I use if I'm changing rim size or tyre width.

http://www.1010tires.com/TireSizeCalculator.asp

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Not sure in your state but here in NSW 70 profile will put you over the legal limit, maximum is 15mm larger rolling diameter over standard. Probably half the 120 prados or more on here are running 70 instead of 65. Depending on tyre, eg mud you dont have much of a choice and with the LT's then its the same situation. Pretty sure you can get a BF in A/T but not LT running 65 profile ?? and no doubt alot of other makes. Insurance ?? I have two sets of rims, the alloys with grandtrecks for around town and everyday driving then the other genuine steel rims will be for off road/trip away/pp days out. Not sure what engine your running but if petrol then as the low range isnt as good as the diesel this will have an effect more so on the petrol engine. Fuel difference I found was more on my petrol then my diesel (this was on my 90 series, one V6 one TD) I ran a higher profile on both my 90's but at the time didnt know about the 15mm rule, wasnt untill I got the 120 and some one on here put up a post which bought it to my attention. Definately give you more clearance, Piggy has already mentioned to you about size difference. I just dont trust insurance companys (never had an issue) BUT if its illegal by the state rules then I suppose if a claim is needed they could knock us back ?? Im defiantely not a stickler for rules but when you have 30/40K plus worth of vehicle and you hit a AMG Merc 100k+ and they say sorry !!!! Id hang myself lol..........Cheers Steve

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

What engine you running Piggy ?? Cheers Steve

[Guest Close Guest]

This issue keeps coming up. I have 265/70 BFGs on my rig. There is no noticable increase in consumption. She will do 10l at 100, 11 at 110, 12 at 120, etc. Mine would do better than 16 towing the camper trailer. This is with ARB bar and 2 inch lift.

The tyres have actually made the speedo 100 accurate. I have confirmed this with Decatur on board mobile radar and GPS and Tru Speed laser, all certified for speed measurement. The 265/65 will have your speedo reading 4 - 6km faster than true speed.

Yep. Each vehicle is different.

I have written results, and speedo checked by SA police laser x 3 (have friends in there) and by a $37k DGPS system and numerous other GPS systems. I also have onboard MONIT rally computer accurate to 10 cms by wheel rolling diameter and calibrated at each rally to a 5-10kilometre route. Have checked this against many speedo checks and it is spot on, not affected by tyre size as its calibrated to the wheel rolling dimaeter.
I know my figures are spot on what i say..
At 110 on speedo I am actually doing 114.7. (On 70 series MTZ).

With my D694 tyres 65 series at 110 is exactly that indicated and actual!
With the grandtreks it came with 110 indicated was actually 108 actual.

For a test recently I drove a 6000km trip 99% highway and changed back to my D694 265/65 tyres.. ARB bar, winch, fridge, one person onboard from Coffs harbour to ADL straight thru averaged 11.5 L per 100.
Did a 3000 km trip recently on same roads and MTZ 265/70 tyres on. Best average was 14.2 L per 100.

Around town my Ultragauge shows me 16's with 265/70 and so does the onboard computer.
Naturally there is a 4-5% error from the bigger tyres throwing the speedo and calcs out.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

The speedo discrepancy will depend on the year of manufacture, my 2005 was spot on with factory rubber, my 2009 was reading fast with factory rubber but the change to 70 series tyres corrected the speedo. With the larger rubber your speedo is corrected but the odomoter reads slow, so you drive more k's than it registers; giving you 4-5% more distance between services and a similar amount of k's less on the ODO when time to sell.

Swings and roundabouts really, plenty of people run 70's tyres and I haven't heard too many complaints.

Cheers Andrew

[MidLifeCrisis Out of control poster! Find all posts View Profile Close MidLifeCrisis]

My 265/70/R17's Cooper st (Non the new Maxx's) read almost exact on my 2009 diesel Grande speedo.

[REV Find all posts View Profile Close REV]

Not sure in your state but here in NSW 70 profile will put you over the legal limit, maximum is 15mm larger rolling diameter over standard. Probably half the 120 prados or more on here are running 70 instead of 65. Depending on tyre, eg mud you dont have much of a choice and with the LT's then its the same situation. Pretty sure you can get a BF in A/T but not LT running 65 profile ?? and no doubt alot of other makes. Insurance ?? I have two sets of rims, the alloys with grandtrecks for around town and everyday driving then the other genuine steel rims will be for off road/trip away/pp days out. Not sure what engine your running but if petrol then as the low range isnt as good as the diesel this will have an effect more so on the petrol engine. Fuel difference I found was more on my petrol then my diesel (this was on my 90 series, one V6 one TD) I ran a higher profile on both my 90's but at the time didnt know about the 15mm rule, wasnt untill I got the 120 and some one on here put up a post which bought it to my attention. Definately give you more clearance, Piggy has already mentioned to you about size difference. I just dont trust insurance companys (never had an issue) BUT if its illegal by the state rules then I suppose if a claim is needed they could knock us back ?? Im defiantely not a stickler for rules but when you have 30/40K plus worth of vehicle and you hit a AMG Merc 100k+ and they say sorry !!!! Id hang myself lol..........Cheers Steve

You can, or at least you could get BFG LT A/T 265 65 17 when I bought mine.

Cheers
Lawrie

[D4D Addicted PP Member Find all posts View Profile Close D4D]

265/70/17 BFG ATs made my '08 100% accurate both speedo and odo with no noticeable increase in fuel economy.

[SWR Banned Find all posts View Profile Close SWR]

Gday timmo23

I am basically repeating what was said above and as "Steve M" said it could cause insurance technicality's if in a prang!

If you change your Tyres from 265/65/17 to 265/70/17 then your speedo will slow down approx 4km (4%).....

By going a taller Tyre your speedo then reads true speed/distance (excluding Tyre wear) and by achieving this you will notice your fuel consumption drop (According to odometer) due to you now loosing 40km per 1,000km (4%).... this is purely because your odometer is now giving you true distance which is now a shorter distance (That has to put a damper on your "True" fuel consumption).

By going the bigger height in your Tyre this will also slightly increase gear ratio so gearing is also higher. (Maybe be noticeable if carrying or pulling heavy loads)... You may also notice your brake pedal slightly harder when pulling-up.

Here is the link below for the holy grail on Tyres in NSW

http://www.rta.nsw.gov.au/registrati...vsi09_rev4.pdf

Minor changes to wheels (pg2)

Wheels up to 26mm wider than the largest optional wheel recommended by the vehicle manufacturer for the
vehicle can be fitted without the need to notify the RTA.

The outside diameter of the wheel and Tyre combination must be no more than 15mm over the largest diameter
wheel and Tyre combination specified for the vehicle.

EG: Approx

265/65-17 - Circumference 30.6 inch = 777.24mm

265/70-17 - Circumference 31.6 inch = 802.64mm

Total Circumference increased by 25.4mm.... That's put me 10mm outside total Circumference legal limit!!

Cheers

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Myn is 05 and is actually out by about 2k the wrong way running factory tyres. My GPS is saying 100 for eg, my speedo is reading 102. I only noticed this back in easter when i thought i got pinged for speeding (no fine so far).......Cheers Steve

[SWR Banned Find all posts View Profile Close SWR]

Speedo reading a side the Police/RTA/Insurance would be paying attention to actual Tyre size and there radar reading at the time.

Cheers

[404pug Avid PP Poster! Find all posts View Profile Close 404pug]

Yes, you can get BFG AT 265/65 in light truck- bought 2 last week. As to speedos,on my 2006 VX the speedo is slow! At 100kph on the GPS the speedo reads 98-99 and this is both on Grand craps and the BFG. On 4 or 5 other cars this same GPS shows that the speedos read 4-5% slow. Go figure! Neil