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MG MGA - Width of Wire Wheels for MGA?

I have a MGA with bolt-on wire wheel conversion hubs.

I am running 48 spoke 4 inch wheels at the moment, but I'm getting the engine beefed up to a stage 2 fast road, and I want to put wider wheels on. The bolt on hubs step the wheel out about 0.5 inch (might only be 3/8).

I was wondering what the widest width of wheel was that I could use with these bolt-on hubs (I don't want it to protrude beyond the body line), I was thinking 5 inchor 5.5 inch, but some people are saying that these are too wide, although I'm sure I saw an MGA with bolt-on hubs running Aston Martin wire wheels.

Any thoughts would be most appreciated.

Thank you,
Grant :-)
G Hudson

Grant,

Depends on the offset of the wheels you get.
either JJ or J offset... forget which gives the most offset to the front.

6inch is about the max. These are JJ from memory.

http://freespace.virgin.net/marka.hester/MKII_April2005.jpg

http://freespace.virgin.net/marka.hester/pic106.htm

but 5.5 are better for road cars.
We run 205 tyres.
You need to factor in the tyre size you want to run also.

<MARK>
Mark Hester

Tires up to 205-60 tires may work on the MGA (maybe), but are smaller diameter than 165-80 size. 205-70 will definitely rub the fenders on bumps. 195-65 or 195-70 is about the largest tire practical for street use with standard fenders.

Original bolt-on steel wheels and 48-spoke wire wheels are 4 inch wide with 1-5/8 inch negative offset. Factory optional 60-spoke wire wheels and Twin Cam (and Deluxe) pin drive steel wheels are 4-1/2 inch wide.

The rear axle housing (and half shafts) for wire wheel and Twin Cam (and Deluxe) is shorter than the disc wheel axle by 7/8 inch each side. If you use bolt-on spline hubs on the disk wheel rear axle the 165 tires may rub on the fenders, and there is no chance of using larger tires.

For correct track width use the disc wheel rear axle and bolt-on wheels, or the wire wheel rear axle and spline drive wheels.

Wheels need to have 1-1/2 to 1-3/4 inch negative offset for correct track width. Given the correct offset any wheel from 4 to 6 inch wide can be used. Best to use a wheel width to suit the tire size.

4 inch wheels accept up to 165 tire size, but the 165 tire prefers 4-1/2 inch wide wheel.

5 inch wheel may accept up to 195 tire size (depending on tire manufacture), but the 195 tire prefers 5-1/2 inch wide wheel.

5-1/2 inch wheel accepts up to 205 tire sice, but the 205 tire prefers 6 inch wide wheel.

In general the rim width should be about equal to the tire tread width (for modern wide tread tires). A wider wheel can provide slightly improved handling, buy it is very unusual to see a wider wheel with smaller tire size (usually only on a rece car with a very conciencous driver).

Using a wheel too narrow for the tire size will cause the tire to roll over on the outside shoulder in hard cornering, leading to rapid wear on the ourside shoulder. It also lifts the inside shoulder such that the end result is functional tread contact about as wide as the rim width (and reduced wear on the inside shoulder).

A narrow wheel will make a wide tire act and handle like a narrower tire, except for the strange wear pattern. So it does not help to install oversize tires on narrow wheels.

Having said that, I must admit that for some years I did run 195-60 tires on 4-1/2 inch wide wheels for autocross competition. This is because 195 was the smallest size available in race rubber compound for a 15 inch wheel, and SCCA limits wheels to standard size in Stock class. Extenuating circumstances.

Now the 195-60-15 race tire is no longer available, 205-50-15 being the smallest size currently available, and no way that would fit on my 4-1/2 inch wide wheels. So I have effectively been legislated out of the sport, unless I want to compete on street tires when the competitors are running on race rubber in Stock class.

If you intend to run your car in formal competition, read the rule book before buying wheels and tres.
Barney Gaylord

Hi Grant

I'm running 5.5 wires with 185/65x15 tyres, no problems at all

Terry
Terry Drinkwater

Barney - great synopsis (as usual).

I think that a 5.5" wheel is all that one can run on an MGA without mods to sheetmetal.

I use that size on my Twincam race car and they fit nicely

see http://www.rhodo.citymax.com/i/non-rhodo/portland.jpg although it isn't that great a pic of the wheels

They allow you to run 185 x 70 rubber.

I was thinking I'll put the race car wheels on the street coupe

http://www.rhodo.citymax.com/i/non-rhodo/coupe-may21-05.jpg

until I put the Twincam back on the track, and run the Comp TA R1s on the street - I don't put all that many miles on the car anyway.

It is going to be a problem when I do go racing again as tire choices are very limited!
Bill Spohn

This thread was discussed between 29/09/2005 and 03/10/2005

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