Tyre replacement

[RichardLewis]

Recently I had to buy new tyres for my '61 Saloon, original size is no longer available in this area and I tried ordering from various manufacturers only to be told to use P175/65R14 as a replacement. This I have done and all appears to be fine on my original rims but I am uneasy as to hard cornering and 'roll off' of tyre, what are your thoughts please?

[Orkney]

Those here will no doubt tell you thats to big and risky so right to be uneasy about cornering.
No expert on the matter but i wouldnt risk that on the previous advice seen on here.

[paulk]

I had a pair of 165 tyres on Maude when we first got her.

It was like driving on flat tyres, every corner (not even fast ones ) were scary as 'ell the roll was incredible and I chopped them in for 145's as oon as I could.

[MoggyTech]

175 on standard rims is a recipy for disaster. 155R14 is easy to obtain and is the max size for the Moggy rim.

[Willie]

On standard rims fit 145 s. 175 s are far too wide.

[RichardLewis]

Thanks to all for your comments, I do appreciate. As I see it I can send out for the proper size and wait or I can buy new rims to fit my new tyres. I will not use these new tyres on the standard rims. anybody for a real deal on my new tyres?

[Kevin]

Also the profile is not helpful either, PM sent.

[myminor1969]

I bought Toyo 155x14 off Bull Motif at this years National. 4 for £100. Local tyre dealer fitted all 4 with new valves and balancing for £25. Car handles brilliantly.

[bmcecosse]

The 175s are far too wide - but you could just about get away with 165 section. Getting hold of wider wheels may not be easy for you - the Minor uses 4" pcd stud and virtually all cars these days are metric - although not sure about Canada. If you do find wheels that fit - let us all know please!

[Ger]

Hi There.
There is a method of working out tyres sizes on wheels, that gives you the largest theoretical tyre size you could safely put on a wheel. don't get me wrong you can get bigger tyres on, but there are 2 problems with it, both related to safety, 1st the tyre may come off the rim under high stress, 2nd your pulling in the sides of the tyre so much to fit the rim that you get a cycle effect on the tyre which rounds the outer contact patch reducing tyre to road contact. both of these problems are bad. So follow this method and you'll be safe. All you do is round the number down to the first tyre size, like so:
4.5" wheels------4.5 x 1.4 x 24.9 = 156.87 round it down = 155
5.0" wheels------5.0 x 1.4 x 24.9 = 174.30 round it down = 165 perhaps you could risk a 175 as it's so close, but personally I wouldn't. What you have to remember is grip is mainly to do with the condition, size and quality of the tyre, now that you know the max size don't skimp on quality when it comes to tyres, the difference is life and death for the sake of a couple of pounds.
This method of sizing works for all wheel sizes, so you can even use it on your new maserati.

[Axolotl]

Excuse my igonrance, but, if I wanted to apply this method to other wheel sizes, I can see where the 4.5 and 5 come from (the rim width in inches?), but what are the 1.4 and 29.5?

[paulk]

I thought minor wheels were 3.5"? that would equate to about 125's

even a 4" wheel would only do about 135's

[Willie]

Paul, the nearest radial size for the standard Minor rim is indeed 135X14
but that size is not readily available although someone once remarked that that was the size on the 2CV?? The reason that is it dangerous to fit tubeless radial tyres which are too wide to the Minor rims is that,unlike all modern wheels, there is no inbuilt groove into which the tyre walls sit which prevents them from being knocked inwards thus losing pressure in the event of kerbing the tyre etc. The formula seems quite accurate to me since the 145 size is widerthan the tyres fitted by the factory to the LP917 4 1/2" van wheels.

[Ger]

Hello again
The tyre conversion thingy was from a wheel manufacturer who I contacted a few years back for advice on what was the biggest tyre I could safely put on 6" rims on my old Nissan Bluebird, sadly I don't remember the company but they said that this was the conversion process used in the industry.
Yes the first number is rim width in inches, the second - I don't really know, perhaps a ratio of wheel width to tyre width, as for the 24.9 well thats easy, 24.9mm to 1 inch, incidentaly the bluebird took 205s.
I hope thats cleared things up, I didn't want to start a war, I only wanted to pass on knowledge which may be of use to some.

GER

[paulk]

I thought 2cv's had 15 inch wheels? But not sure, the width sounds right though.

I'm assuming the old crossply sizes were the width of the tyre in inches (but with some sort of 80 or 90% factor for the tyre height like radials) so 5.20 x 14 would be about 132mm wide.

Did the LP917's run on 5.60's (About 142mm)

[Willie]

Yes, the factory size was 5.60X14" on the LP 917 s and yes, cross ply
widths are in inches.

[RogerRust]

Yes the first number is rim width in inches, the second - I don't really know, perhaps a ratio of wheel width to tyre width, as for the 24.9 well thats easy, 24.9mm to 1 inch, incidentaly the bluebird took 205s.
I hope thats cleared things up, I didn't want to start a war, I only wanted to pass on knowledge which may be of use to some.

GER

Actually 25.4 mm = 1 inch

If you use wheel width X1.4 x25.4 the answer comes out closer to my experience.

[rayofleamington]

The worst I've ever seen is 185 on a saloon rim!

Did the LP917's run on 5.60's

yes that sounds right from memory, however Radial tyres were available by the time the (4.5") LP917's were introduced on the 8CWT commercials. These ran with 155 tyres and sometimes 165 tyres. However depending on the brand, 165's could foul the front trunnions due to very limited clearance (although many different tyre sizes were used - Sometimes different on each wheel like one Van I bought!)

Willie is indeed correct - Minor saloon rims are 3.5" wide. Add approx 20mm per side (to allow for the tyre wall shape) and 135 is the nearest standard tyre size. I ran 135's on my first Minor but sadly they went out of production.

The Minor specialists sell 145's for saloon rims and 155's for the wider rims - although many people are happy with oversize 155's on saloon rims, I don't like the poor cornering that they give.

Your tyre place should not have fitted a 175 on a 3.5" rim - by doing this they could end up in court if you had an accident. This may also invalidate your insurance as you are using a tyre that is outside of its recommended application. This is of course the 'worst case' as it's only fair to point these things out when saftety is concerned.

[TeHoro]

Recently I had to buy new tyres for my '61 Saloon, original size is no longer available in this area and I tried ordering from various manufacturers only to be told to use P175/65R14 as a replacement. This I have done and all appears to be fine on my original rims but I am uneasy as to hard cornering and 'roll off' of tyre, what are your thoughts please?

In the USA the following vehicles used the same stud pattern as a Morris Minor. Dunno if they were ever sold in Canada, but you might be lucky

GM L-body
Buick Skyhawk '75-'81
Chevrolet Vega, Monza '71-'81
Pontiac Sunbird, Astre '76-'81
Oldsmobile Starfire '75-'81

[Kevin]

In the USA the following vehicles used the same stud pattern as a Morris Minor

Well something new learnt every day I though all PCD`s were Metric by the mid 70`s.