Measuring wheels

rossk · Post by **rossk** » Sat Apr 15, 17 4:58 pm

Hi

May seem like a silly question but I just need to check. I'm looking at the magnum 500 wheels, I've measured my stud pattern and the pattern is 5 4.5.

The wheels on the website state they're 15x8 with a 4 1/2 backspace, am I correct in assuming that from the face of the hub to the outside edge of the wheel would be 3 1/2 inches?

I.e. 4 1/2 + 3 1/2 = 8 (which is the 8 they refer to in the 15x8)

charger01 · Post by **charger01** » Sat Apr 15, 17 5:59 pm

The 8" is the width of the rim / wheel.

rossk · Post by **rossk** » Sat Apr 15, 17 6:06 pm

Thanks that what I though but wanted to check

Charger · Post by **Charger** » Sun Apr 16, 17 11:01 am

some good info here about wheel data ...

http://www.raceways.co.uk/wheel-data.htm

Pete · Post by **Pete** » Sun Apr 16, 17 11:07 am

Not all companies measure Backspace the same way - Vintiques measure it slightly differently.

rossk · Post by **rossk** » Sun Apr 16, 17 11:21 am

Thanks for the info, it's the tyres that are actually throwing me off, I had normal factory steel wheels, look like 14x5 with a 3 1/2 backspace, but when you add the width/bulge over the rim of the tyre it adds about another 1 1/2 inches each side so making the total width of the wheel & tyre about 8 inches

So approx 5 inch back space and 3 from face of hub to outside wheel arch inner. Currently have 235/60/14 tyres.

My backspace on the car is actually 6 inches but that is right up to the leaf spring, and approx 3.5 to the inner of the outer wheel arch.

So I'm thinking to be safe getting 15x6 with a 4 inch back space, meaning total backspace including tyre would be 5 1/2 & 3 1/2 to outer wheel arch

Blue · Post by **Blue** » Sun Apr 16, 17 11:39 am

Sounds like you will be very tight on the outer side. The other thing you need to consider is ride height, stock or lower and you could be in trouble. If you look up at the outer lip you will see how quickly the inner arch curves inwards, the tyre might clear the lip only to hit the inner arch a couple of inches up.

rossk · Post by **rossk** » Sun Apr 16, 17 11:46 am

I need to measure it all accurately And I've found a lot of good websites that give detailed instructions for measuring wheels, but none of them seem to take into account that the sides of tyres bulge outwards and are not perfectly flat to the face of the wheel.

I could go for more modern wheels 17, 18's etc with flatter tyre sidewalls which would make life easier but I think I want to keep what I consider to be the muscle car look (personal opinion) of smaller wheel, fatter tyre with white writing.

Pete · Post by **Pete** » Sun Apr 16, 17 11:53 am

I agree with you there; it's personal taste, but I do not think modern wheels and tyres suit the older muscle cars.

You DO have to measure very carefully. We even mocked up spare wheels and tyres on my Dart. When I ordered, it was still too close for comfort and I had to select 235 tyres on the rear and not the 255's that EVERY site in the 'States said would fit.... The bodies of the old cars are not built that precisely or consistently - varying greatly from side to side.

rossk · Post by **rossk** » Sun Apr 16, 17 11:57 am

Yes I'm tempted to either make a wheel out of cardboard or tyy and find an old set of trashed wheels and tyres I can buy or borrow as a guide.

It's a shame wheel/tyre companies don't offer this but I'd imagine there are so many different wheel & tyre combos that it's just not feasible

Blue · Post by **Blue** » Sun Apr 16, 17 12:08 pm

I always try to match the wheel width to the tyres tread width, looks best that way IMO. Going an inch narrower on the rim gets rid of a lot of the sidewall bulge for tight spaces. As opposed to the current trend for using rims that are far too wide for the tyre so that the rim sticks out and looks as stupid as possible....

rossk · Post by **rossk** » Sun Apr 16, 17 12:43 pm

Just another quick head scratcher which someone may be able to explain? All the research regarding tyres suggests that my 235/60/14 means that my tyre width should be 235mm, the profile height (edge of wheel rim to edge of tyre) should be 60% of the tyre width of 235, so 141mm

However when I get a straight edge either side of the tyre and measure across it's only 210mm, and side wall appears to be approx 126 which supports the tyre being a 210 as 60% of 210 is 126

Any ideas??

Blue · Post by **Blue** » Sun Apr 16, 17 1:24 pm

Yes different manufacturers seem not to stick exactly to the formula, which is why I try not to use 2 tyres by different manufacturers on the same axle. With American tyres you can normally get the dimensions on their website, so I'll use that and check for a specific make rather than a generic size and buy those. Northants tyres website is quite good for sizing information and so is Summit.

rossk · Post by **rossk** » Sun Apr 16, 17 1:36 pm

Thanks Blue, my plan was to get the lot from Northants. Currently making use of the day and getting on with another task, new handbrake cables being fitted today!

rossk · Post by **rossk** » Mon Apr 17, 17 8:09 pm

making up some cardboard wheels! Best way i can think of to make sure i don't order the wrong sizes.