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MG MGB Technical - Fitting 15' dia minilight type wheels

Apoligies if there are threads dealing with this but I haven't been able to find any. I have just moved this from the MGB General Section where I did get some useful info but feel I mat get more detail here

I would like to fit some 15" dia wheels (with appropriate size tyres - dia and profile ratio) to my MGB. I have read stuff that says you need to be careful about offset to ensure they will fit within the wheel arches. Has anybody any experience of fitting minilight style wheels to the B? Thanks in anticipation.

John
John Turner (Midget & MGB)

I have 15 inch superliteslites on my 79 roadster
The full spec is 15x6 4x114.3
I have no issues.
C Vine

A friend of mine has tried to persuade me to fit 15'' wheel to my GT, as he claims that this gives better gearing etc with the non-OD gearbox, he prefers it to the OD cars. Can I ask, is this part of your motivation in switching to 15'' wheels?

Sorry for the slight sidetrack!

Piers
Piers Colver

picture of my 79 roadster with 15" superlites

C Vine

Piers, since most people who use 15" wheels fit lower profile tyres, the difference in gearing becomes negligible. In my own case I have 195/60 x 15 tyres. Compared with the original 165/80 x 14 they are actually 0.2" SMALLER in diameter than the standard tyre. I had to fit 15" because of the Hoyle independant rear suspension which fouls on a 14" rim.
Mike Howlett

Thank you for that Mike - my friend turned my head by going all technical! He claimed that a non-OD BGT on 15'' wheels was 'the one to have'; I need new wires but was thinking 14''. Thanks for the input and sorry, John, for the tangent.

Piers
Piers Colver

The 15x5.5" Minator wheels are offset a little more (about 3mm I think) to the outside than the 14x5.5 and can result in contact between body and tyre on bouncy corners. There is enough in the centre of the wheel to safely remove 2mm from the mounting face and avoid this.

C Vine - very intersting. What tyres are you running/have you rolled your wheel arches? All the Superlites I've seen fitted seem to need this as 6" is quite a tight fit in the standard arch.
Paul Walbran

195/60R15 Yokohama tyres
And the wheel arches have not been rolled. I seem to have plenty of room.
C Vine

Fitted 15" wheels to every B I've ever had, never had a problem. With the right tyres rolling radius is almost the same. If the wheels are correct for a B then the off-set should be right to put the King Pin and contact patch relationship as it was before. The wrong off-set will change the scrub radius which affects the steering load and tyre wear.
Allan Reeling

To clarify: The tyre-body contact I noted isn't just bouncy corners, it's bouncy corners when pushing hard. Say half a dozen times on a spirited 400 miles of back-country road. Tyres 185-65x14, same rolling radius as 165x14.
Paul Walbran

Thanks Guys, my motivation is that I have wanted for 20 years to have a set of nice looking wheels and now have the wherewithall! Also, I am considering in the future the Hoyle IRS as I was aware that this requires 15" rims. Intersted in the various profiles ratios used - does the 60 profile give more of a harsher ride (less flex in the walls)? The rims I am considering are something like these http://www.ebay.co.uk/itm/MGB-6x15-Alloy-Wheels-x-4-Minilite-Design-NEW-/140857902948?pt=UK_CarParts_Acc_Wheels_tyres_Trims_Car_Rims_ET&hash=item20cbc90764 with the polished rim. Am not sure now about the 6" width though

C Vine your Superlights also look the business
John Turner (Midget & MGB)

John- Flex in the sidewalls is more a matter of the design of the particular tire. I run 195/60R15 Michelin Pilot Exalto tires and the ride is quite acceptable. 6" width is OK with 195/60R15 tires, but 5.5" will also work. Just be careful where the offset is concerned, otherwise the scrub radius will be unequal and steering effort will increase.
Stephen Strange

I had decided to go for the Superlite wheels and as I live (fairly) close to their address in Gloucester I went to see them. The address on their website is now a block of flats, they are not answering the phone number that works (there is another one on their website which is 'not recognised') and they have not replied to an e-mail. Does anyone know if they are still trading?

John
John Turner (Midget & MGB)

John, Superlite certainly were trading a couple of years back, but I know a lot can happen in a couple of years.

I have their splined charcoal wheels on mine.


Hal Adams

Hal, they look really nice - shame I don't seem to be able to buy any!
John Turner (Midget & MGB)

Owning an MGC which came with 15" wheels, after awhile an MGB looks definitely tinker toy-ish in comparison.

The rear wheel arches are the limiting factor on offset and width, but otherwise I prefer 15"

You have a choice - go with modern low profile rubber that matches the approximate rolling radius of the stock 14" tire, or go with taller aspect ratios to get a longer effective diff ratio.

Too bad so few North American cars came with OD!
Bill Spohn

This thread was discussed between 30/04/2013 and 31/05/2013

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