tyres!

[snowylebongo]

my bongo is running on 195/70r15c all round, and seems ok apart from not liking the lorry ruts on the motor way very much, just wondered if this was a common option as i know they came from japan with a wider section back tyre, have noticed speedo is about 4mph out but now i know i can live with that!.

[Northern Bongolow]

see the plate on the door b post.
they should have 195 70 15 on the front, and 215 65 15 on the rear, the rears are slightly lower profile but a little wider for the rear end weight and stability. BUT ARE THE SAME OR VERY CLOSE TO THE SAME ROLLING RADIUS.
with 195 70 all round they are too narrow and a little tall so maybe unstable for the rear.. the insurance company may not like someone fitting non standard tyre sizes on. .
some fit 215 65 15 all round.

[David Edwards]

Quite a few of us are running 215's all round, I have for years, seems better and they are £40.oo a tyre her too, fully fitted,lol.

[windywatson]

Hi, I have the reccomended size tyres on my van and as you have said about your van not liking the lorry ruts on the motorways, mine doesn't like them ither.
Was going to place a post my self to see if others were experiancing the same, I think the issue with the dislik of lorry ruts is more to do with the wheel base of the vehicle. It seems to me that the distance (width) of the wheels apart is the issue. If the wheels are not running in the bottom of the ruts then they are fitting to run straight as they are both trying to run down to the bottom the gradiant causing that slight feel of snaking.
There are some sections of the M1 that is so bad I wont drive in the slow lane because it's not pleasent to drive in.

Cheers

[jaylee]

WINDYWATSON, do you drive full time 4 wheel drive...?

[windywatson]

Sorry, forgot to say V6 petrol rear wheel drive only.

Cheers

[jaylee]

Blew my theory out the water then.... I had full time 4x4 with the 195 70 15 on the front, and 215 65 15 on the rear suffering with similar symptoms... "215's all round sorted it.

[mikeonb4c]

Hi, I have the reccomended size tyres on my van and as you have said about your van not liking the lorry ruts on the motorways, mine doesn't like them ither.
Was going to place a post my self to see if others were experiancing the same, I think the issue with the dislik of lorry ruts is more to do with the wheel base of the vehicle. It seems to me that the distance (width) of the wheels apart is the issue. If the wheels are not running in the bottom of the ruts then they are fitting to run straight as they are both trying to run down to the bottom the gradiant causing that slight feel of snaking.
There are some sections of the M1 that is so bad I wont drive in the slow lane because it's not pleasent to drive in.

Cheers

Track, not wheelbase, is the word you are looking for (i.e. narrow track) and yes, someone had to point it out to me too once, on here

And I think you are right. Try rapid left and right steering wheel motions on an AFT Bongo (don't try this at home kids, or at least not on a public highway and at speed ) and it becomes obvious you are in a vehicle with high C of G, narrow track, and fairly soft suspension. So if a rutted road forces the vehicle to keep altering its track, you're likely to experience a greater sense of snaking esp when, as it is instincitve to do when trying to keep in lane, you try and correct each displacement and usually only end up acting in phase with the cause - in airplanes the equivalent is called pilot induced oscillation.

I'm not sure I'd accept though that insurance companies could weedle out of supporting an insurance claim unless they could prove a direct link between the cause of an accident and that small difference in tyre spec (and out of interest is there any large print from Mazda that warns of dire safety implications if there is any deviation from the recommended tyre spec?).

What does matter is that Bongo drivers get to know their vehicle, its limitations, and anticipate situations so as to keep it within those limitations as far as is possible. Explore the envelope cautiously when you can, but not on a busy highway. And try and avoid situations which might oblige you to do a high speed swerve (e.g. drive at less 65 mph, where the Bongo does its best fuel economy, avoid bunching where possible, and enjoy the view from on high)


A Bongo's got to know its limitations

[snowylebongo]

firstly thanks to all the responces on my recent tyre question, iam however a little worried now as to wether going for the narrower section tyres was a good idea (my local tyre dealer advised me onto these saying there was little difference and these tyres were much more commonly available, should i have trouble far from home) i suppose the question i want to ask is " am i safe on the option i am running at the moment" . the bongo is my passion and hobby but i do want my family to be safe in it. thanks

[snowylebongo]

me again! iwas asked but forgot to answer, the bongo is a 2 wheel drive 2.5 diesel auto friendee

[mikeonb4c]

firstly thanks to all the responces on my recent tyre question, iam however a little worried now as to wether going for the narrower section tyres was a good idea (my local tyre dealer advised me onto these saying there was little difference and these tyres were much more commonly available, should i have trouble far from home) i suppose the question i want to ask is " am i safe on the option i am running at the moment" . the bongo is my passion and hobby but i do want my family to be safe in it. thanks

Personally, I think the garage is right and you should be fine. Just get to know, and drive within, the limitations of your Bongo. A sports car they are not.

[scanner]

Hi, I have the reccomended size tyres on my van and as you have said about your van not liking the lorry ruts on the motorways, mine doesn't like them ither.
Was going to place a post my self to see if others were experiancing the same, I think the issue with the dislik of lorry ruts is more to do with the wheel base of the vehicle. It seems to me that the distance (width) of the wheels apart is the issue. If the wheels are not running in the bottom of the ruts then they are fitting to run straight as they are both trying to run down to the bottom the gradiant causing that slight feel of snaking.
There are some sections of the M1 that is so bad I wont drive in the slow lane because it's not pleasent to drive in.

Cheers

This problem isn't restricted to Bongos, as there few cars that have the same track as the HGVs that cause the ruts in the first place.

To get round I just drive to one side, usually the verge side, of the ruts, the Bongo is narrow enough to do so without hitting anything on the verge/hardshoulder. If anything is parked on the hard shoulder just pull out enough to miss it.

[windywatson]

Hi,

With respect to what tyres your garage may recommend. The tyre fitters that I use have a method of calculating the difference between tyres. It is some sort of ready reckoner they use on their PC. They enter the recommended tyre dimensions and then i put the next available or readily available nearest size and it does a percentage comparison.
The recommendation is that if they come out within no greater than 6% variation (may by 3% cant remember what they said now) your OK to use. Not sure if the percentage is a legal recommendation or tyre industry one though.

Someone one out there may put us right on this.

Cheers.

[scanner]

There are lots of tyre size calculators available on line, many have previously been posted on here.

Such as
http://www.tyresave.co.uk/tyresize.html