Tire Size

[Maddy_110]

We decided on the BFG KM3s in 7.50X16 (tall and skinny) for our 110. We have been very impressed with them on and offroad. They are surprisingly quiet considering how aggressive they are.

Where did you find those that you could get that tire size?  Isn't that more of a European sizing?  The 7.50X16 is what the manual recommends for my 130, but that's back where we started when I asked what that size equivalent is in Canada. Hmm...  They are nice tires though.  I'm debating between those and the KO2s still...

The KM3s are one of the rare tires available in that size here in North America. They are unicorns though! Pretty hard to find. I managed to find two sets - a friend is running them on his old Series IIa as well.

[Red90]

Are you running 255s?  I was just doing a conversion, and the 265 and 235s are basically 31.6" and 31.7" respectively, and the 255 is 33.1".  I like the sound of that, but with it being a bit bigger in diameter, would that cause rubbing anywhere in a full lock turn?

Yes.  It is a common size used on Defenders. All the recommendations I'm giving are without modifications but only with the correct rims.  With Wolf rims, they work.

The rubbing on the radius arms Trevor mentioned above is meant to be stopped by adjusting the steering stop.  You should always adjust the steering stops so that the tires barely clear the radius arms.

7.50x16 - 31.8" x 8.7"
235/85R16 - 31.7" x 9.3"
265/75R16 - 31.7" x 10.5"
255/85R16 - 33.1" x 10"
285/75R16 - 32.8" x 11.3"
Anything larger will require some minor modifications.

[GR8PMKN]

The KM3s are one of the rare tires available in that size here in North America. They are unicorns though! Pretty hard to find. I managed to find two sets - a friend is running them on his old Series IIa as well.
[/quote]

That's a pretty great find!

[GR8PMKN]

Are you running 255s?  I was just doing a conversion, and the 265 and 235s are basically 31.6" and 31.7" respectively, and the 255 is 33.1".  I like the sound of that, but with it being a bit bigger in diameter, would that cause rubbing anywhere in a full lock turn?

Yes.  It is a common size used on Defenders. All the recommendations I'm giving are without modifications but only with the correct rims.  With Wolf rims, they work.

The rubbing on the radius arms Trevor mentioned above is meant to be stopped by adjusting the steering stop.  You should always adjust the steering stops so that the tires barely clear the radius arms.

7.50x16 - 31.8" x 8.7"
235/85R16 - 31.7" x 9.3"
265/75R16 - 31.7" x 10.5"
255/85R16 - 33.1" x 10"
285/75R16 - 32.8" x 11.3"
Anything larger will require some minor modifications.

OK.  Good info.  So I'll look up to see if I can find the 255s in the tire I decide on.  I understand that you can adjust the radius arms to avoid rubbing, but what I don't want is to have to adjust them such that my turning radius suffers even further.  Do you know if they would work with no adjustment?

[Trevor]

OK.  Good info.  So I'll look up to see if I can find the 255s in the tire I decide on.  I understand that you can adjust the radius arms to avoid rubbing, but what I don't want is to have to adjust them such that my turning radius suffers even further.  Do you know if they would work with no adjustment?

To adjust the steering to prevent rubbing it is just a single bolt adjustment if I recall correctly. Pretty straightforward with nothing to fiddle with on the radius arms. Mine rub at full turn in reverse. John is correct though, it really should be adjusted out if you run into the problem.

[Red90]

OK.  Good info.  So I'll look up to see if I can find the 255s in the tire I decide on.  I understand that you can adjust the radius arms to avoid rubbing, but what I don't want is to have to adjust them such that my turning radius suffers even further.  Do you know if they would work with no adjustment?

Most likely there is no difference in turning radius between a 265/75 and a 255/85.  The chance of your steering stops being set properly right now are low. In any case, you won't notice any difference.

[GR8PMKN]

Maybe I could play with the stops and even tighten my turning circle slightly (if there's room to do so) once I get the new tires on.  I'll have to look into that...

[Matt H]

First, you had your tyres analyzed by a tyre shop because of vibration and they told you you need new tyres. No surprise there. I'd get the tyres balanced properly and look for a less biased a second opinion.

But let's assume you really do need new tyres immediately and you want to go with something that fits with your future build plans for the Land Rover.

Well, your Wolf wheels are not going to work, I'd sell them to someone that owns a 90.

With a long wheel base 130 and a heavy camper that you want to take off road you are going to need to build around a much larger tyre size and a much wider track width.
I'd suggest a minimum of 285/75R16 and ideally larger/wider. Unless your idea of "off road" is a two track forestry road, weight and wheelbase are going to make anything close to a stock width and height tyre a real chore in the rough.

The skinny tyre thing only really works well on a light short wheel base unit.

Also, this isn't going to be cheap to do properly. 

My 2c

[GR8PMKN]

First, you had your tyres analyzed by a tyre shop because of vibration and they told you you need new tyres. No surprise there. I'd get the tyres balanced properly and look for a less biased a second opinion.

But let's assume you really do need new tyres immediately and you want to go with something that fits with your future build plans for the Land Rover.

Well, your Wolf wheels are not going to work, I'd sell them to someone that owns a 90.

With a long wheel base 130 and a heavy camper that you want to take off road you are going to need to build around a much larger tyre size and a much wider track width.
I'd suggest a minimum of 285/75R16 and ideally larger/wider. Unless your idea of "off road" is a two track forestry road, weight and wheelbase are going to make anything close to a stock width and height tyre a real chore in the rough.

The skinny tyre thing only really works well on a light short wheel base unit.

Also, this isn't going to be cheap to do properly. 

My 2c

Thanks for the 2c, Matt.  Pardon my ignorance, as I'm still learning about these Defenders.  What's wrong with the Wolf wheels?  Too skinny?  I thought they were supposed to be good!  As for the tire shop - of course I took what they said with a grain of salt.  This particular shop has been honest with me before saving me a bit of money, but of course they'd like to make a sale.  Even on the day, they could have analyzed and balanced each wheel like I asked them to, but they only analyzed one and stopped there to tell me they weren't worth wasting any more of my money on going any further.

Anyway, what we think might be a tire balance/quality problem (the vibration above 90km/h), I'm still thinking it might be a prop shaft problem.  Reason being is that I was driving on the highway yesterday, and finally had a chance to roll down some hills at speed and without having my foot on the gas, the vibration goes away.  As soon as I'm on the gas again, it returns.  If it were a wheel issue, wouldn't the vibration still exist doing 100km/h coasting down the hill??

I've been doing some reading and research, and apparently the quality of the long 130 rear prop shaft is hit and miss, even from the factory.  The metal might be too thin and it starts to flex/resonate causing a wobble at higher speeds.  I'm going to look more into that.  It doesn't help that whoever undercoated my truck before I owned it got that crap all over the shafts too, which I think is affecting the balance of them.  I know it's not the u-joints because I've replaced all 4.  Maybe I should buy a new heavy duty rear prop shaft and try that instead of the tires for now... Hmm...  I watched a video from Britania Restorations and he had the same issue on his 130.  He switched to a new shaft (15 pounds heavier than the old one), and the problem disappeared.  "Like night and day." he said. Hmm...

[binch]

Maybe the propshaft needs balancing?    You can test it at a drive line shop.   

[Red90]

Drive it with the rear prop removed and see if it still vibrates.

[GR8PMKN]

Maybe the propshaft needs balancing?    You can test it at a drive line shop.

I'll look into the cost of that.  Hopefully it's not more than just buying a new one...  ::)

[GR8PMKN]

Drive it with the rear prop removed and see if it still vibrates.

Good suggestion.  In my research, those who have tried this have found it successful in troubleshooting.  I suppose if I find there's no vibration when it's off, while I have it off I could take it into Pat's Driveline or something to have them check it out if not too pricey.  Are there any precautions I need to take before driving around without a rear prop shaft?  I suppose I need to consider the parking brake drum...

[Red90]

Put the nuts back onto the drum where the shaft came off.

It will drive like crap in front wheel drive so don't mix that up with the vibration you are checking.

While it is off make sure the big nut on the transfer case output flange is tight. And check the diff flange to make sure it is not loose.

[Trevor]

When you have the driveshaft off it's easy to check the u-joint for proper (and improper) movement. The shaft could be out of balance, but u-joints are a more likely candidate and can be verified at home.