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MG Midget and Sprite Technical - oh no, not another wheel and tyre question

I'll apologise for this straightaway but in my defence, I've searched the archives and can't find a straight answer to this...
Also, this is a request for information. I know some people have strong opinions on using wider wheels but, without meaning any offence, I'm really not interested in opinions - just the information :-)

so.
firstly.
Can anyone state categorically what inset / offset should be specified for a 6 X 13 minilite style alloy.
and
secondly
What tyre size best replicates the rolling circumverence of the standard 145/80 13 (i'm guessing at something like 165/70 13.


p.s. if I get these wheels I'll be selling a set of five 5.5 x 13 alleycat (wolfrace slot lookalikes) in need of some refurbishment (watch this space)
graeme jackson

YOU BASTA*D !!!

I cant belive you would raise such a question....oh wait, you mentioned wheels and tires, NOT wheel bearings, yeah no problem no offence here...your good to go.

Hahaha

no info here...sorry

Prop
Prop and the Blackhole Midget

You can play with tyre sizes here http://www.miata.net/garage/tirecalc.html
Geoff Ev

Graeme,
sorry I don't about the 6x13" wheels or why you'd want them, less practical for wet and snow, it's the tyre compound that gives the grip - anyway this link might help and is for matching 145/80/13 - http://www.carbibles.com/tyre_bible_pg4.html

the tyre manufacturer will have a range of wheel widths that they recommend for their tyre usually the optimum and one size either side

I'd have thought a wide tyre like 190/60 (not that exists) would be the width to fit the wheel and and close to matching 145/80/13

and this will give you great info about tyres - http://www.carbibles.com/tyre_bible.html

ETA: typing whilst others post again, these links will give you loads of info, just because you can get something to fit on paper doesn't mean it's a good choice
Nigel Atkins

Perhaps should have mentioned; the front suspension is Frontline and it's a RWA car.

And thanks for the carbible link Nigel - very informative.
graeme jackson

four pages on that link if you look at the top of the page

I too have the l*ing b*stards front and rear suspension and RWA and now I have the ride height I want thanks to Kim Dear at Magic midget (and not LB or Moss) I'll be looking at 145/80 tyres next time (155/80 now and 155/70 and 155/80 previously)
Nigel Atkins

Id becareful that you dont get to much tire...ive heard it can create alot of resistance and loose its corning abilities, speed and agility

Prop
Prop and the Blackhole Midget

It might even snap a rear axle shaft
Prop and the Blackhole Midget

tyres seem to be almost as much an art as a science and you can get variances between tyres that are same make and model but different sizes

the sidewalls in themselves and in relation to the wheel and perhaps even pressure make a difference, also how this compares to the compound grip and less extent tread pattern

in Europe we now have very simplified tyre labeling that may correspond little to real life use and previous experience of the particular tyre, tyres that are known to be good in the trade have lower ratings on the new labeling system

my previous tyre didn't score that well on the labeling system but I'd say is was a very good tyre in my experience - it's now not available from the manufacture that now has a new replacement tyre that scores better in the new labeling, in an ideal world this new tyre would indeed be better than the last but I'm guessing that might not be the case

I've recently swapped to a tyre that has a similar score to my previous tyres and the difference is marked in grip, ride and handling characteristics, the previous tyre was noticeably better

however the wet braking is noticeably better with 7mm of tread over about 2.5mm and I'll be going back to changing tyres when they get down to 3mm tread
Nigel Atkins

I put 6" Cosmic rims on the Frogeye with 205 X 60 tyres back in 1972, and ran it all year round for the next 10 years. I don't recall the offset, but to get them on I needed 1)10 mm spacers and 2)longer wheel studs, 3)space back the steering arms, 4)shorten the rack and 5)track rod ends 6)limit the steering rack movement 7)reduce the height of the nut on the TRE 8)use sprung brake hose protectors and then 9)add wheel flares because the tyres stuck out of the body. I ran with 18psi, but it never broke a halfshaft or spun it in the wet and the ride was fine.
F Pollock

great points that I was wondering about

both yours and Graeme's sound like they might not have been everyday use cars

if it was 10 years on one set of tyres then you didn't use it much at all
Nigel Atkins

sticking to the original question, Midland sell a JBW 6X13 with an offset ET13. Am i correct in thinking this would give a backspacing of around 4 inches (depending on the thickness of the rim) ? - I've read in the archives that up to 4 1/2 inches is 'just' ok to avoid rubbing the rear springs.
if I get a chance later I'll take some measurements with my existing wheels - they have a stamp INSET 8MM.
graeme jackson

You could make up a cardboard template based on the dimensions from Midland Wheels - adding the tyre of choice and try it against the front and rear hubs. That way you could adjust the offset to determine what's best for you.

F Pollock

I asked Peter May the same question when I was looking at sticking with 13" wheels.

"For racing we use the 6" wheels which do require some wheel arch extensions, these are ET16."

BUT it will depend on your brake set-up and any oddness in your car. Ask the wheel manufacturer - each one I emailed gave a slightly different answer but were very helpful.

In the end I went with 5.5" wheels with 175/65R14 UniRoyal rain expert tyres. The combination works well for my RWA K-midget.
Johnathan

I bought 5" wide Revolution wheels from Kim at Magic Midget. They are fitted with 165/70 x 13 tyres and they look good and perform well. Also they go in the square rear arch without body modifications.

Mike Howlett

This is from Paul Walbran (Posted on my thread asking a similar question) - albeit skewed towards 14" wheels:

Some diameters from my tyre chart in case you need to explore options further:

origianl 145x13: 565mm
165-70 x 13: 560mm
175-70x13: 575mm
175-60x14: 565mm
175-65x14: 585mm
175-70x14: 600mm

As you can see I choose to 'gain' 20mm overall tyre diameter to help with my low exhaust. I went to 14" to get a better range of H-rated tyres. I have not experience any rubbing/fouling of bodywork but my car is a MkIII RWA.
Johnathan

This thread was discussed between 04/12/2012 and 09/12/2012

MG Midget and Sprite Technical index

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