Tyre sizes

I may be being a bit thick but how does this make the speedo more accurate?. I would have thought the speedo would be more accurate with standard tyres on and less accurate with bigger ones

With standard tyres on my speedo ran about 10% over. Think they may well set up the speedo for the optional 31" tyres that were a factory option.

With 31s on the speedo reads about 5% over.

Cheers

[Leodis]

Only drawbacks are a slight loss of acceleration due to the larger rolling circumference, speedo being a bit more accurate (now I don't even think I'm going fast) .



Cheers

I may be being a bit thick but how does this make the speedo more accurate?. I would have thought the speedo would be more accurate with standard tyres on and less accurate with bigger ones

[Morr]

.....which is a 13mm differance or just over 5inches......

ahem, think theres a decimel point missing

[poppy986]

Hi there all,if any help 265/75/15 has a rolling circimference
of 2362mm.
31/10.5/15 has a rolling circumference of 2375mm which is a
13mm differance or just over 5inches.
If you are not sure on the accuracy of your speedo you can take
the car to a Tachometer testing station where by using the
rolling road at set speeds you can see the reading on the dail
compaired to the true speed.

Or find your local road speed inforcer? Chris

I was thinking along the same lines:

Slower acceleration,
More accurate speedo reading,
Faster speed due to larger circumference therefore better MPG.

However, the difference in diameter of the 31" to the 265x70 can't be so much that the above is noticeable can it?

The 'slight wobble' in the steering wheel is a concern... wont this cause wear on the steering linkages?

Hence the post for anyone with these tyres to give their first hand experiences.

Actually the difference in Circumference is reasonably large. The diameter is 1.4 inches larger so by working out the circumferences by 2 x PI x R it comes out that the difference in circumference is 4.3 inches which is about a 4% difference which concurs with the change in my speedo reading of 4% - 5% ( checked with a GPS).

I knew that maths at school would come in useful one of these days.

I have no wobble in my steering wheel. Any wobble could be caused by the tyres being out of shape. With a more chunky tread this is possible if one of the lugs is out of true, and it may change as you put some miles on. Teering wobble may cause extra wear on the steering and suspension components so it should be checked out. Get a tyre place to put it on the balancing machine and see if the tyre is running true.

Cheers

[marky]

265x75x16" do catch the front mudflap bolts. 265x70x16" are a better option

[AndyLala]

According to Toyota (what do they know) 31" was the max.
As you will no doubt find from other posts, side steps, mud flaps, etc. get in the way when you go over 31".

Also something about rubbing inside the front arch as well, so offset needs to be smaller (or something like that)...

andyL

[Poleyhants]

Is the 31" the biggest that can be put on a standard Surf?




Regards,

Poleyhants with a distinct lack of wobbliness.

[Gizmo]

No wobble with my 31" MT's at all

WObble may be too much..but in general i felt the difference in the steering wheel between the road going Geolanders on the vehicle and the Colway ATs

[Koi]

I replaced the Bullet's 265/70/15 road tyres with 31x10.50x15 BFG All Terrains, and I didnt have any issues at all. MPG and speed were not impacted at all, and there was definately no "wobble". There was not even any noticeable change in road noise.

On our grey surf we went from 235's to 31" and there was definately an impact in terms of the power needed to reach the same speed, and in terms of the speedo. Again though - no "wobble"

No wobble with my 31" MT's at all

[Linda]

What are the drawbacks of fitting 31 x 10.5 x 15 as opposed to 265 x 70 x 15

I believe the 31" tyres are slightly bigger in diameter than the 265x70

I replaced the Bullet's 265/70/15 road tyres with 31x10.50x15 BFG All Terrains, and I didnt have any issues at all. MPG and speed were not impacted at all, and there was definately no "wobble". There was not even any noticeable change in road noise.

On our grey surf we went from 235's to 31" and there was definately an impact in terms of the power needed to reach the same speed, and in terms of the speedo. Again though - no "wobble"

[icsys]

I was thinking along the same lines:

Slower acceleration,
More accurate speedo reading,
Faster speed due to larger circumference therefore better MPG.

However, the difference in diameter of the 31" to the 265x70 can't be so much that the above is noticeable can it?

The 'slight wobble' in the steering wheel is a concern... wont this cause wear on the steering linkages?

Hence the post for anyone with these tyres to give their first hand experiences.

[mat1]

i was speeking to a work mate and she has a landi 90 and put bigger tyres on it. she reckons she can go faster due to the greater circumfrance with the same power. is this true.....might it contrabute to better mpg.....?

Only drawbacks are a slight loss of acceleration due to the larger rolling circumference, speedo being a bit more accurate (now I don't even think I'm going fast) and more difficulty getting the mother in law in the back (especially since I removed the side steps.

Road noise is a little more but I've got M/Ts on mine.

Cheers

[Gizmo]

What are the drawbacks of fitting 31 x 10.5 x 15 as opposed to 265 x 70 x 15

I believe the 31" tyres are slightly bigger in diameter than the 265x70

The only thing I have found with fitting these is a little wobble in the Steering Wheel due to the tread being AT (all-terain) on the rims and hence the gap between the ridges is more so just alittle wobble.

The measurement equates to the Width x Aspect Ratio (percentage of the tyre wall x 15 diameter)

Go on and treat yourself!