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MG MGB Technical - Wheel Sizes

I have been running low profile Falken tyres on my '67 MGB for 12K miles and have decided to return to standard size Pirelli in the interests of a better cruising ride. Because my car has a bigbore (2100cc) engine and other tuning mods acceleration has not been affected despite the higher rolling tyre diameter. The car looks better with the wheel wells being filled out more in keeping with the original.
My question is 'whether I should have opted for 15" wheels and stuck with a lower profile tyre for possibly better handling?"
Peter

Peter
I run OE GTV8 wheels in Summer with 185 65s which is much more comfortable than the Winter 15" SAAB wheels with 195 55s. The handling is better with Winter wheels but I always look forward to changing back.
Roger

PS The arches are un-modified
RMW

Peter, in my opinion and that's all it is, unless yoiu are really intending to throw the car around and be an absolute hooligan then standard profile tyres are adequate for road use. Yes big wheels small tyres do look good, but they are more suited to modern machinery (again my opinion only!).

Whilst it is not a B, I run 70 section (ie normal aspect ratio) tyres on the race midget, as opposed to low profile tyres. These tyres are a control tyre for the series, we can get drift out of these tyres, but that is half the fun of balancing the power and the turning in at corners. However I must admit that we all drive them hard, and I would not even think of doing what we do on the circuits on the roads.

So whilst everyone is chasing low profile, stiff sidewalls etc, I personally don't think it has any benefit in normal road usage.

Andrew.
Andrew McGee

Oh and I should add that I run a Jubilee BGT for my everyday road car, that is wearing 65 section tyres at the moment (on Gold painted V8 Dunlop wheels), I intend changing to a standard section tyre at the next tyre change, research shows that Mark 1 Golf GTi tyres are the same size as original equipment.

Andrew
Andrew McGee

I changed from my stock 14" x 4.5" x 60-spoke MGB wheels with 175/70 tires to 15" x 5.5" 72-spoke wheels with 195/60R15 tires. The handling and steering were transformed! Steering is heavier with the wider tires, but at speed the steering is far more crisp and with less side to side sway, which I attribute more to the lower profile tire than to the stiffer wheels.

The ride is a little harder with the heavier wheels and shorter sidewalls but it isn't too bad. I would not go much lower profile than 60 in fear of the rear end hopping too much on rough roads.
Steve Simmons

Thank you guys for your input. Will run these tyres out and then try 15x5.5 inch wheels with appropriate rubber.
Peter (Aus)
Malski

Hi,

You can use that program to predict the suitable size for your car.

http://www.stuegli.com/tiresize.htm

In fact MGB was equiped with 165x14(read 165/82x14). The best fit will be 165/65x15, as it is less rigid than 60 ratios. For wheels you can also use Datsun 260-60-80Z 15"models or Toyota Supra.

Cheers,

JGC
Jean Guy Catford

Performance wheels are good. Made in Adelaide.
I've got 15inch by 6 super lites on my V8 conversion and they look very good. They polish the rims on them which was a very nice suprise . They do have 10 spokes on the 15 inch and also the centre is a little wider. http://www.performancewheels.com.au/super_lite_wheels.htm
I glued MG badges over the superlite logo on the centre covers. The badges on the ROSTYLE wheels are exactly the right size for this.
If you can afford the very best (I can't!) the Dayton wire wheels are stunning & may be fitted to bolt ons via their centre spin on adaptor hubs.
Tyres-
Bought a set of Michelin XM1's. Low rolling resistance. About $150 each. Had them on 6 months or so now.
They are V rated 195 by 60's. No clearance problems.
Very good in both wet and dry conditions. The wet weather grip was suprising given that I had heard Michelins were not good in this area.
They are also quiet and have a high treadwear rating so should last about three times longer than my previous set.
Peter

WheeloOff set is 24P for MGB's
Peter

24 P? My shop manual reads 22mm.
jim

I installed 15" x 6" alloy wheels on my '67 gt. The tires are 195 55 15 and are about 5% smaller radius than stock. The car is lowered about 3/16".

With stock front suspension and fiberglass rear springs the car corners like it is on a railroad track. Ride is comfortable. The glass rear springs help a lot.

I'm using a 1/4" wheel spacer on one side of the car. It will rub occasionally if I push it to the limit in rough road conditions. I have not modified the rear fenders in any way.

The comparison between stock wheels & tires and this setup is so far apart it is not comparable. I can keep up with any modern car through the twistys. The steering is a little heavier around town but still quite acceptable.

My experience with different tires on other cars is that the brand & model tire is extremely important. Modern hi performance tires will have amazing traction, transient response, and wet road traction.

Check out the testing at the Tire Rack web site. It is very informative.

Modern hi performance Tire & wheel technology will more difference to your driving experience than a supercharger.

Barry
Barry Parkinson

15 by 6JJ 24P is stamped on all five wheels. Perhaps this 24P is specificaly appliciable to Performance (superlite, minilite replica wheels). Whatever the case there is no rubbing either on the inside or outside of the guards.
The wheels were around $200 each through MG workshops in melbourne.
I should add my car is a rubber to chrome bumper conversion with the ride lowered to chrome bumper spec'.
Peter

Hi,

Have a look in the archives. Low profile ires are not ver good for old B suspension's design. It will stress a lot that old car on the long run...
Cheers,

JDC
Jean Guy Catford

Peter -
As has been noted, much of depends on your intended useage. Obviously, a higher-profile tire will normally yield a softer ride at the expense of cornering abiliity. Higher profile wheels will also give you better braking and fuel economy. If, however, you are interested in maximizing handling and braking, then a lower profile tire is better.

I vote for the Superlites too; I run 15x6 Superlites running 225/50/15 BF Goddrich G-Force T/As. I also have modified fenders and wheel spacers. I use my car only for weekend drives, track days, etc. It does ride more harshly, however, IMHO, the ride is more than acceptable. Particularly when you factor in the incredible handling gain.

All tires are a compromise to some extent. I, too, used the Tirerack website to help in my selection.

Martin Connolly

Peter and others, I fitted about (two hours ago) a set of the new K/on Superlites. They are 15*6 fitted with 185-65-15" V rated Bridgestones. They are now available in 8 spoke in 15" and look great. The hub is fitted from the inside so its smooth on the outside. Denis
DENIS H

Peter-
Speaking from experience, I can state that 15" wheels with P195/60R15 tires will definitely improve the steering response and handling. However, if you're going to stay with 14" wheels and P185/70R14 tires, consider adding a Panhard rod to your rear suspension. It will improve tracking considerably when driving hard thru the curves. Boosting the damping rate on the front end by 20%-25% will also help.
Steve S.

It comes down to how you want to use your car. If you want to look period authentic that is one approach. If you want a car thats fun to drive and loves the twistys, you have no choice but to upgrade wheels and tires. It is without doubt the most bang for the buck ( or the pound).

Once you upgrade wheels and tires, - only then - you can then think about upgrading suspension components.

Obviously getting your suspension into good repair and working condition must be done, whatever your choice is.

The truth is, with modern wheels and hi performance tires the B handles real well. (The rubber bumper cars are another story.)

Barry
Barry Parkinson

This thread was discussed between 24/09/2006 and 30/09/2006

MG MGB Technical index

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