Wheel/tyre size combo

Technical questions and answers about the Mazda Bongo

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pollyden

Wheel/tyre size combo

Post by pollyden » Tue Apr 24, 2012 10:40 am

Im sure this has been asked a zillion times. . . but, my Bongo has 7"x16" wheels with 225/50x16 tyres.
Is this the correct tyre size for this wheel size & is this the correct combo for the Bongo. . . combo for the Bongo. . . i feel a song coming on . . . :D
MountainGoat
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Re: Wheel/tyre size combo

Post by MountainGoat » Tue Apr 24, 2012 11:13 am

Standard Bongo wheels are 15" wheels but many people run their Bongos with larger aftermarket wheels. What you have to look out for is that the minimum loading for the front wheels should be 92lbs and the minimum loading for the rear wheels should be 96lbs.

Then it gets more complicated especially if you have a 4WD. There should be a minimum rolling (circumference) difference between the front and the back wheels if you want to avoid making a mess of the viscuous coupling of the 4WD. One of the experts on this subject should be along soon to explain this to you more clearly. Or you can use the seach facility Wheels & Tyres where you will find many past posts on this subject.

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helen&tony
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Re: Wheel/tyre size combo

Post by helen&tony » Tue Apr 24, 2012 11:25 am

Hi
The diameter of yours are 29 mm smaller than standard size wheels/ tyres, and at 60 MPH you will be doing 62 MPH
Also check the load rating, as stated above, and on same size wheels , ensure they are above 96
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Helen
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pollyden

Re: Wheel/tyre size combo

Post by pollyden » Tue Apr 24, 2012 11:52 am

Thanks MountainGoat.
Yes, i am aware of the front/rear circumference issues with the 4WD system & the load ratings on wheels/tyres etc (i actually trained as a mechanic many moons ago & am currently a service advisor at a main dealer, so get involved in this sort of thing a lot) - but i was just wondering if the wheel/tyre combo was an ok combo for the Bongo.
I bought the vehicle with the aftermarket wheels on there, but will soon need new tyres, so just wanted to check the size already fitted was correct.

I have a "hubcap" missing from one of them, but dont know what make the wheels are, so am finding it hard to find one :(

Many thanks me deres!
pollyden

Re: Wheel/tyre size combo

Post by pollyden » Tue Apr 24, 2012 12:05 pm

helen&tony wrote:Hi
The diameter of yours are 29 mm smaller than standard size wheels/ tyres, and at 60 MPH you will be doing 62 MPH
Thats interesting.

Are you saying that the SPEEDO under-reads at 60 but im actually doing 62?
Or the speedo over-reads at 62, but im actually doing 60?

I am aware that most vehicle speedos over-read & obviously, if it over reads with the slightly larger standard tyres, it will over-read less, with the reduced circumference.
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dave_aber
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Re: Wheel/tyre size combo

Post by dave_aber » Tue Apr 24, 2012 12:12 pm

If the wheels are too small, then you won't be travelling as fast as is indicated.
If the wheels are too big, you will be travelling faster than indicated.
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pollyden

Re: Wheel/tyre size combo

Post by pollyden » Tue Apr 24, 2012 12:18 pm

Yes, obviously. . . i was just wondering weather the Bongo is blessed with a speedo that is naturally accurate, or if it under or over-reads as standard.
pollyden

Re: Wheel/tyre size combo

Post by pollyden » Tue Apr 24, 2012 12:20 pm

I have a motorbike that indicates about 67 at a genuine 70 - yet my Saab indicates 74 at 70.

The bike has an under-reading speedo while the car has an over-reading speedo.

By the sound of it, the Bongo speedo over-reads as standard :D
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dave_aber
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Re: Wheel/tyre size combo

Post by dave_aber » Tue Apr 24, 2012 12:25 pm

Generally speaking, Bongo speedos do overrread - but there are so many wheel / tyre combos and speedo modifications / puls correction chips / faceplates / GA5R mods that they are all different.
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Re: Wheel/tyre size combo

Post by pollyden » Tue Apr 24, 2012 12:36 pm

dave_aber wrote:. . . they are all different. . .
Its called "character" . . . ! :lol:
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Re: Wheel/tyre size combo

Post by Poohbear » Tue Apr 24, 2012 1:06 pm

It is actually illegal in the UK to have a speedo that under-reads i.e. it reads a lower speed than you are actually doing. This is the reason why all new vehicle speedos over-read because manufacturers err on the 'over' side so that all vehicles produced are within the law, even though they may all read slightly differently (within manufacturing tolerances).
pollyden

Re: Wheel/tyre size combo

Post by pollyden » Tue Apr 24, 2012 1:19 pm

Ha ha - the bike in question IS 21 years old. . .
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Re: Wheel/tyre size combo

Post by scanner » Tue Apr 24, 2012 2:20 pm

MountainGoat wrote: What you have to look out for is that the minimum loading for the front wheels should be 92lbs and the minimum loading for the rear wheels should be 96lbs.
Not lbs [-X

Just a load index of at least 92 front and 96 rear and they are both way over that in lbs.
http://www.blackcircles.com/general/load-rating

92 = 630kg (1389lbs)
96 = 710kg (1565lbs)
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