Recommend me a tyre size?

[dave88sw]

Hi,

I've got an 88" that's currently sat on a set of standard steel wheels and 7.50 XZL tyres.  I've just had a set of standard rims banded to take them from 5.5" to 7" and i'm now looking at tyres to get mounted to these rims.  A few years back, i had a set of 265/75r16's on it and they were fine other than heavy steering and they'd just catch the front of the rear wheel arch if loaded up.  At the time i didn't mind too much because it was pretty rough, dented all over and brush painted matt black but i've since spent a lot of money on straighter body panels and painted it the original marine blue.  The only thing is, they were insa turbo special tracks, so not only were they very aggressive tread and big shoulder blocks, they were also remoulds (which seem to be slightly bigger than a virgin tyre, i guess because they take a 265 carcass and then mould another layer of rubber over the top?).

Is anyone successfully running 265's on a series swb with no rubbing?  I would go for 235/85r16's but i do like the look of bigger tyres.  Currently decided on cooper discoverer stt pro's unless anyone can change my mind?

Thanks

Dave

[Jon White]

I’ve got 285/75/16s on mine, but then it is slightly modified.....

[dave88sw]

Haha, i know it's possible but i don't want to modify too much.  It has standard height parabolics and standard bodywork so i'm hoping i can squeeze some 265's in without too much bother.

I've been trying to return it all to standard but i can't resist some bigger wheels, i just love the look of them.

Like this:

[AV8R]

255/85R16's on 6,50x16 rims. Parabolic spring with military length shackles. Very happy with this combination.

About as large as you can go without fender flares, they fill up the fender area quite nicely.

[Snagger]

Do you have PAS?  I found the steering got considerably heavier going from 7.50s to 235s, so 255 or 265 must be quite firm.  That said, I did have aftermarket wheels at the time, which creates an offset that makes things heavier.  Which was the bigger factor, footprint or scrub radius, I don't know, but the steering on the lightweight with 6.50s and standard wheels felt incredibly easy by comparison.

[AV8R]

10 hours ago, Snagger said:

Do you have PAS?  

No, it is just the original steering box in good nick ;-) I do keep an eye on tyrepressure (2,2 Bar) and there's a lightweight engine up front. The V6 weighs about 80 Kg less compared to the Rover 4 . Off set on the rims is about 0, helps too.

11" TLS brakes from a 109 where mounted up front to cope with the larger radius wheels. Braking is very good.

[Daan]

Another vote for 255/85/16. I had this on my old 88" when it was leaf sprung. Great size, as narrow as it gets on this diameter, so good for turning circle and steering lightness. Larger diameter good for off road clearance and on road speed. Also drilling the top kingpins and fit grease nipples did wonders for steering lightness on my old series.

[AV8R]

That ^^^ reminds me . . . . . . . .top king pins were converted to roller bearings over 35 years ago. Less friction = less effort ;-)

[dave88sw]

Thanks for the suggestions. I don't have power steering but i am trying to collect all the necessary parts to convert it (probably going the P38 box route).  I was ok with the old insa turbos, only really noticed the steering being heavy when parallel parking.

255/85r16's sound like a good option, although seemingly not a common size and they appear to be a bit more money.  My banded wheels had the full 1 1/2 inches added in front of the centre hub so they have increased the offset.

So nobody is on 265's? I only ask because i can get my hands on a set fairly cheap.

[dag019]

On 12/9/2017 at 7:14 PM, dave88sw said:

So nobody is on 265's? I only ask because i can get my hands on a set fairly cheap.

I have 265/75's on the 110 but I personally don't like wide tyres on a series and have a set of 7.50's on mine. I think they are more in keeping with the period characteristics of a series motor.

However the difference between 255/85 and 265/75 in practical terms you will notice driving the vehicle is very little. The diameter (and therefore the gearing) makes more difference to an under-powered series than the width. The only thing you will have to check with the wider 265 tyre and your offset is that it wont catch the wing at full articulation. But there is a 109 near where I work running 265 mud terrains so it is certainly possible.

[AV8R]

1 hour ago, dag019 said:

However the difference between 255/85 and 265/75 in practical terms you will notice driving the vehicle is very little. The diameter (and therefore the gearing) makes more difference to an under-powered series than the width. 

It ís the same with braking. The larger the diameter, the weaker the brakes.

If your 88" still has the original 10"brake drums I strongly advice to invest in some 11" brakes from a 109. Besides the 10% larger diameter, the linings are 50% wider and both shoes per drum are leading. Late Series III already have them fitted from the factory but if yours is somewhat older it is worth checking.

I used to run true 900x16's and had no problem braking these 36" big rubber flywheels. Mind you the 900's are over 15Kg heavier, each ! There's a lot of energy stored in them at 100Km/h.

[Jon W]

235/85/16 on mine on 7 inch modular give it perfect fill of the wheel arches without sticking out. I think 265 would stick out on these rims

 

 

[Snagger]

On 11/12/2017 at 9:32 PM, AV8R said:

It ís the same with braking. The larger the diameter, the weaker the brakes.

If your 88" still has the original 10"brake drums I strongly advice to invest in some 11" brakes from a 109. Besides the 10% larger diameter, the linings are 50% wider and both shoes per drum are leading. Late Series III already have them fitted from the factory but if yours is somewhat older it is worth checking.

I used to run true 900x16's and had no problem braking these 36" big rubber flywheels. Mind you the 900's are over 15Kg heavier, each ! There's a lot of energy stored in them at 100Km/h.

Absolutely true on the diameter effect on braking (in addition to bigger tyres aquaplaning more easily).   As far as 11" brakes on late 88s is concerned, I think it was only the front axles that got 11" drums, and they were the rear brakes from a 109 with double acting cylinders and only one leading shoe per wheel, just like on 10" brakes.  I think the twin leading shoe system with two separate slave cylinders per wheel was only fitted on 109s.  I stand to be corrected on that, but my 1980 Lightweight had that set up - 11" front and 10" rear, all with double-acting slaves.

[dave88sw]

She's already got 11" twin leading shoes on the front and is wearing a set of 7.50's currently so very similar rolling diameter to 235's or 265's. May upgrade to discs if i can scrape the money together.

On balance i think 235/85r16's are going to be the best compromise. 

Thanks all.

[Snagger]

Dave, discs are easier to maintain and clean, and can be a bit easier to control on slippery surfaces, but they won't give more braking effect if your drums system is in good condition.  You have to be doing a lot of wading and mud driving for a disc upgrade to be worthwhile,  in my view.

[Ally V8]

Dave, can't offer any sensible advice about your tyres ! But I did mention to Phil that I have done your crank pulley for you.Ready when ever you want to collect it.Give me a call.