13 replies to this topic

[jim4eva]

Hi,

If I were to replace my 5.5x12 wheels with 7x13 wheels,
what do I need to do? I am aware that the wheel arches need to be cut,
but what else needs to happen? better wheel bearings?

thanks!

[Cooperman]

You need to be able to accept the fact that the wet weather road holding will be less good, especially ultimate braking, and that the general 'driving feel' is likely to also be less good. The 13" wheel is not a performance enhancer, quite the opposite, but some, just some mind you, seem to think that 13" 'look' better although others thing they look decidedly odd. Wheel bearing life and suspension component life will also be reduced. there are no 'special' bearings available. Cutting the body will also increase the rusting potential.
It's just personal choice, as are so many things Mini.

[jim4eva]

thanks for your response,

some very useful information there which I will certainly think about before making my decision

thanks!

[Cooperman]

thanks for your response,

some very useful information there which I will certainly think about before making my decision

thanks!

Yes, I'm a bit biased as I think the 13" look horrible.My good friend in the village here has a Sportpack which had 13" wheels, but after he drove one of mine on 12" he changed his to 5" x 12" Minilites with the earlier type arches. In fact cutting the original wings for the 13" had caused so much rust we had to fit new wings.
I think 13" might be OK for racing where ultra-wide sticky slick tyres can be used in the dry, but for the road those very wide tyres are poor in the wet due to insufficient contact pressure and in snow or ice they are worse than useless.

[MRA]

13" wheels and tyres out brake 10" anyday, they also give you a better footprint for better traction off the line....

Right lets put some old wifes tales straight.... if they are NOT a performance enhancer howcome they wear out wheel bearings ???

13" wheels and tyres do NOT cause any more rust to your bodywork that is down to shoddy workmanship.....

Agreed they are less useful in snow or ice, however we don't get too much of either really do we .. ?

Edited by mra-minis.co.uk, 23 May 2011 - 04:57 PM.

[Cooperman]

13" wheels and tyres out brake 10" anyday, they also give you a better footprint for better traction off the line....

Right lets put some old wifes tales straight.... if they are NOT a performance enhancer howcome they wear out wheel bearings ???

13" wheels and tyres do NOT cause any more rust to your bodywork that is down to shoddy workmanship.....

Agreed they are less useful in snow or ice, however we don't get too much of either really do we .. ?

They wear out wheel bearings because of the added cantilever effect of moving the tyre centre-line outboard. If the approximate weight on each front wheel is 400 lb and the offset is a further 2" over, say, a 5" wide rim, that is an added basic torque to be resolved by each front wheel bearing of around 7.5 lb.ft. When cornering and over any bumps, that figure is multiplied. They also screw up the basic as-designed steering geometry.
They may give better traction off the line on a dry day when doing a 'drag-type' start. But only in the dry.
They will be fine with sticky slick racing tyres on a dry track as that sort of tyre is designed to work at lower contact pressures when the rubber is warm. But you can't use a slick on the roads. On a racing car the added wheel bearing and suspension wear issues don't matter anyway.
A 13" won't outbrake a 10" 'anyday'. It might do so in the dry on a very smooth road. It won't outbrake a 10" in the wet, on a bumpy surface, on ice, in the snow or on any slippy or muddy surface.
Yes, the rust is down to shoddy workmanship or, in the case of the Sportpack, very poor production processes.

[MRA]

The cantilever effect ?

The load on the bearing is due to lots of effects, static and dynamic, however by far the greatest is due to dynamic effects, the difference between a 10" & a 13" tyre rolling radius is not a great deal, thus the torque effect whilst cornering is similar if the grip is the same, so if the grip is so superior on a 10" tyre why do 13" tyres wear out wheel bearings so readily ???

I have been using 13" tyres on my Mini since the early 80's and wheel bearings when fitted correctly last for years, my last set have been on my Mini with 195/45-13" for over 25,000 miles wiyhout any issues..

Granted skinnier tyres are better on ice, snow, mud..... but to quote the OP

Quote
Hi,

If I were to replace my 5.5x12 wheels with 7x13 wheels,
what do I need to do? I am aware that the wheel arches need to be cut,
but what else needs to happen? better wheel bearings?

thanks!
Quote

The OP wants to know what to do to change to 13" wheels and tyres not your personal opinions on them....

Yes you can get better wheel bearings, as the OP's car could quite easily have ball roller bearings in the front and rear hubs, and changing to taper roller bearings will be an upgrade

[4my]

I have 13 x 7 deep dish starmag alloys with sportspack arches which i changed from 12" minilites.

... I much prefer the 13" and can't say i've noticed much difference in the cars performance they just look so much nicer! other than the fact the car feels more sturdy

[jim4eva]

wow,
just logged back in and I've been pleasantly surprised to see all this discussion,
very useful stuff!
thanks guys!

[Cooperman]

The offset loading is the cause of higher wheel bearing wear with a wider wheel and that does not only apply to the Mini. In a straight line the weight on a wheel can be deemed to be acting through a point mid-way between the inner and outer tyre edges. With a 7" wide wheel as compared to a 5" one, that load line will be 2" further out as if the inner edge moved further inwards it would hit the damper. Thus there is an added leverage acting on the wheel bearing which that bearing must resolve. When applying other dynamic loading, that leverage will multiply with the bump loading. As the rolling rads are virtually the same, within about 4%, the rotational forces won't be significantly different unless the wheel/tyre combination is heavier.
The grip is not superior on a 165 tyre over a 175 (or wider) so long as overall average grip is considered. However, there are times when the very wide tyre will lose out, and those have been identified - in the wet, on slippy or slightly broken/bumpy surfaces, on ice, in snow. The trouble is that it's at those times that the loss of grip can be critical, especially in the wet.

[Cooperman]

The tyres will just sit centrally on the wheel whatever the tyre width, 145 or 165, so the mean centre line of the tyre is the same.
You'll love the 165/60 A539 as it's a superb tyre and on the original Minilite 4.5" wheel you will probably have the best wheel/tyre set up for a car with 8.4" discs. They will give much better road-holding than the Pirelli.
My buddy in our village changed from 13" to 12", but he has the 5" wide with Falken 165/60x12 and loves it. I've driven it with both 13's and 12's and know which I prefer, especially in the wet.
When i had the A539's on a hot 998 a year or so back I found that a pressure of about 32 psi was excellent, but experiment from about 28 to 34 to see what bsuits your driving style best.

[Wil_h]

The problem is that when people slate 13s they are generally talking about 7x13s. If you use 5.5 or 6x 13s then you get all the advantages of the grip in the dry and you lose little in the wet.

In most cases there will be no differance between any size trye (available for the mini) regarding grip in the wet, only when there is lots of standing water will a narrower section tyre have an advantage. And who cares which one is better in the snow?

Again the wheel bearing issue may have some basis on 7" wide wheels , but with 5.5s and 6s the wheel position is pretty much the same as any other 12 or 10" wheel.