Bongo Fury

i have a four w/drive and i run all 4 the same size and condition.
BUT do not cross rotate your tyres as some of the tyres are directional.
you can swap same side front to back,on each side but do not cross them.

some tyres are not rotation conscious,so please check first.

i think some on here are misunderstanding what the tyre sizes mean
can i try to clarify whats going on as i understand it.

the 215 or 195 refers to the width only,which in this context is totally irrelevant

the main factor is the height

65 or 70 is the height this is the transmission killer.

Northern Bongolow wrote:i think some on here are misunderstanding what the tyre sizes mean
can i try to clarify whats going on as i understand it.

the 215 or 195 refers to the width only,which in this context is totally irrelevant

the main factor is the height

65 or 70 is the height this is the transmission killer.

No,I completely disagree, both width and Aspect Ratio (Height) are very relevant, the diameter of the tyre increases as the width increases, even keeping the aspect ratio the same.

e.g. a 205 x 65 x 15 tyre has a 2% smaller rolling circumference than a 215 x 65 x 15 tyre, calculator here: http://www.alloywheels.com/TyreCalc.asp

I have another calculator but it's on my work PC atm, so will have a check there as well. I think you may be right there munroman.

Now I thought I saw somewhere, may have been on here, can't remember off hand, a diagram showing to swap RR to LF and RF to LR. Obviously this is if the tyre is not a directional one and they're of the same size.

munroman wrote:

Northern Bongolow wrote:i think some on here are misunderstanding what the tyre sizes mean
can i try to clarify whats going on as i understand it.

the 215 or 195 refers to the width only,which in this context is totally irrelevant

the main factor is the height

65 or 70 is the height this is the transmission killer.

No,I completely disagree, both width and Aspect Ratio (Height) are very relevant, the diameter of the tyre increases as the width increases, even keeping the aspect ratio the same.

e.g. a 205 x 65 x 15 tyre has a 2% smaller rolling circumference than a 215 x 65 x 15 tyre, calculator here: http://www.alloywheels.com/TyreCalc.asp

wow thanks for that.just had a play and put some hypotheticals in thats blown me and my theories out of the water. sorry guys.i really didnt know that the circumference increases with the width. back to the drawingboard.

yeah, that's the tricky bit.

The middle number represents the sidewall height as a % of width.

So for standard Bongo tyre sizes 195/70/15 and 215/65/15

70% of 195 is as near to equal as you can get to 65% of 215.

For 4wd the difference is crucial to the operation of the Viscous Coupling which gives drive to
the front. Tyre circumference should be as near to equal as pos front to back.
Standard rears are fractionally bigger than fronts ( to promote engagement of VC , from what I
understand.)
If your fronts wear out more than rears then circ will be changing for the worse.


For those who may not know: first number is tyre width in mm
second is sidewall height as a % ( of width )
third is wheel ( steel/alloy ) diameter in inches.

The circumference needn't change (drastically) with width if the % number changes proportionately.

If you go for bigger alloys ,ie third number 17 instead, then the % number will be even smaller to
preserve original circumference.

eg: 245 / 45 / 17 has a 5mm smaller circ than 195 / 70 / 15 ( according to one site I checked ).

These are prob too wide for Bongo by the way. Just an eg.

We had 195s on front now 215 65 15 all round. Front tyre wear was a prob for us uneven tyre wear. Tracking made no difference. Tyre wear is now good with 215s all round. Plus a lot better ride. Our rear diff also went when we had different tyres front and back and bongo did scrabble more when going round sharp corners up steep hills.

Northern Bongolow wrote:

munroman wrote:

Northern Bongolow wrote:i think some on here are misunderstanding what the tyre sizes mean
can i try to clarify whats going on as i understand it.

the 215 or 195 refers to the width only,which in this context is totally irrelevant

the main factor is the height

65 or 70 is the height this is the transmission killer.

No,I completely disagree, both width and Aspect Ratio (Height) are very relevant, the diameter of the tyre increases as the width increases, even keeping the aspect ratio the same.

e.g. a 205 x 65 x 15 tyre has a 2% smaller rolling circumference than a 215 x 65 x 15 tyre, calculator here: http://www.alloywheels.com/TyreCalc.asp

wow thanks for that.just had a play and put some hypotheticals in thats blown me and my theories out of the water. sorry guys.i really didnt know that the circumference increases with the width. back to the drawingboard.

I did try & tell you a while ago

Here's one with pictures

http://www.kouki.co.uk/utilities/visual ... calculator

i know but i have selective hearing
joking aside ive done college projests on tyres,been around tyres all my working life,driving on them thankfully,not fitting them.just shows how you can think you know summat,but yet not know the whole story.
thanks for the education guys.

I have an update, I have driven nearly 1000km this weekend.

I drove 250km with a caravan to Suffolk, back without it to Bedfordshire, did it again to Suffolk without it, and back with the caravan to Bedfordshire. Don't ask why, it was a pain but educational.

Without the caravan, my Bongo is happy as larry. It accelerates fine, temp (with modified gauge) reads a steady 12 o'clock regardless of hill or speed as it should, and I am pleased that it seems to be doing what I would expect a healthy Bongo to do. Even the shake at 60mph has died down, suggesting that the tires are not castling any more and they indeed do look flatter. It cruised at 70-80mph with no fuss or drama, and very little shake on the steering wheel.

With Caravan, different story. The temp gauge is the biggest clue, it settles at 1 o'clock and up to 2 o'clock with a gradient. It pulls okay, holds 60mph fine, climbs gradients seems to be working as I expect. I have found after about 2 hours, there is a glitch. It is like someone puts the handbrake on. On my last leg of my driving, I had the caravan and was flying along, 60mph no problem, kept it up for nearly 2 hours, then a gradient, and the Bongo slowed to 50mph. It could not hold 60mph, and the temp started to climb. It dropped one gear, then two looking for drive. It got near to H and I surrendered then pulled over to let the engine cool. When idling, the temp came right back down to 12 o'clock, and I sat there for 10 minutes with the engine idling, then carried on. The problem could still be felt, but then cleared after 10 minutes or so, and the transmission felt better. I gained speed and lost temp on the gauge.

I expect a bit of raise in temp with a caravan, but this hitting of a wall is odd. I can only guess is is one of my differentials, probably the front getting too hot and binding. That is how I am viewing it at the moment.

Can anyone point me in the general direction of a person or garage that know Bongo transmissions really well? I would like to tow another caravan or something just to eliminate that as the possible problem. I doubt it it is the caravan wheels, when I stopped on the side of the road, the tires were hot but not the hubs, so I do not think the brakes were dragging. I guess I need to take it to someone who drives a lot of Bongos to see if mine is odd, and let someone else take a view on what is going on. I have no experience of driving other bongos and have nothing to compare what mine is doing as being right or not. It just does not seem right to me.

no one got any ideas what might be going on, or anyone who I should be talking to and taking the bongo to?

Hi, I think member Alaric? is an expert on gearboxes, I know he is very keen that additional transmission cooling is given when towing, could it be that the gearbox oil is overheating after 2 hours towing?

After your incident, have the diffs had an oil change?

Are you still running 2WD? in which case I can't see how the front diff is going to cause the symptoms you have. Alacrity is the auto-box guru, definitely worth quizzing him on a likely gearbox fault.

Good luck.

Muzorewa wrote:Are you still running 2WD? in which case I can't see how the front diff is going to cause the symptoms you have. Alacrity is the auto-box guru, definitely worth quizzing him on a likely gearbox fault.

Good luck.

Hi Muzz, my logic is that the front diff will still be getting driven by the front wheels, if anything is amiss after the tyre incident then there may be a chance that a damaged bearing or similar is overheating and causing friction, though I agree the more likely issue is the gearbox, and Alaric is very pro extra cooling for the gearbox oil when towing.