Couple of Newbie Techie Questions!

[joeldrummer79]

So just to reiterate.... The best thing for me to do is replace my current tyres with 225/55/R17 with a load rating above 96 all round. This way I will not have to replace my wheels, am within insurance spec and will not cause any mechanical damage to the vehicle (being a 4wd)

So does everyone agree this works?

I DO want to be safe and protect my camper

[mikeonb4c]

So just to reiterate.... The best thing for me to do is replace my current tyres with 225/55/R17 with a load rating above 96 all round. This way I will not have to replace my wheels, am within insurance spec and will not cause any mechanical damage to the vehicle (being a 4wd)

So does everyone agree this works?

I DO want to be safe and protect my camper

Probably best, and 55 should give a nicer ride. I'm very happy with my Maxxis all season tyres:

viewtopic.php?f=1&t=73056&hilit=Maxxis

The excellently priced wrexham supplier i used doesn't seem to have 55s in stock at present, but does have 50s at an excellent price. You could maybe replace the 95 loaded tyres with a pair of these?

http://www.ebay.co.uk/itm/172405730736

[joeldrummer79]

Thanks for this info, greatly appreciated!

Doubt I'll be able to purchase them this month though as have to sort the timing belt, auxiliary belts, water pump, stat, drain coolant, flush and bleed , full service and two swivel seats!!

[joeldrummer79]

Hi. I'll help with the bit I know most about.
The critical thing with the 4WD is having the tyres the same size or, to be completely accurate the same rolling circumference. Your tyres will make the Bongo a tiny bit undergeared but will be fine. When it comes to replacing them you can go for 225 50 17 which will make the gearing stock ( use a 195 70 15 spare if your spare wheel is 15 inch) or (which is what we've done) fit 225 55 17 tyres which make the gearing a little taller but allow more choice for tyres that will make the most of the 4WD such as the excellent Michelin Latitude Cross

Hi Tony

I'm looking at tyres at the minute and youre absolutely right, 225 50 17 has less choice and obviously load rating is still within spec but with this size I do know what I need to put on my 15" spae (cos you told me )

That said, I'm looking at 225 55 17 all round but can you tell me what size spare I would need on my 15"? Cheers

[Bob]

Pop your tyre sizes into a circumference calculator like this one:

http://www.tyresave.co.uk/tyre-size-calculator/

I can't remember the small size difference allowed, but it's one or two per cent I think.

[mikeonb4c]

Interesting thread here

https://www.pistonheads.com/gassing/topic.asp?t=734625

Where someone says:

Any fairly modern car should have a plate somewhere under the bonnet which gives the maximum gross vehicle weight along with the maximum front and rear axle loads.

Bearing in mind the axle load is spread over two tyres, then so long as the individual tyre rating is no less than half the max axle load, then you should be fine and its hard to see how anyone could argue otherwise.

You should check the numbers, although its quite unlikely you'll have a problem, as the manufacturer will have spec'd in a generous margin.

For example, I just had a look at my Mazda MX5. Max axle load (rear) 680kg, tyres are 82 (475 kg each). Therefore the tyres on that axle could take 950kg (assuming equal load).

There is a margin per tyre therfore of (950 - 680)/2 = 135kg.

Its suprising how easily you can exceed the individual axle load (esp. at the front if driver and passenger are er.. "amply built" The inspectorate have been known to camp out at the roadside with axle weigh pads, lots of vans getting caught at the mo.

A table of tyre load ratings and axle loads can be found here.

https://www.blackcircles.com/general/load-rating

From all this, you might be able to construct an argument that persuades your insurers the 95 tyre load rating is adequate, once you've established what the Bongo axle loads are.

Bongo axle weights can be found here:

https://www.allansvehicleservices.co.uk ... cation.pdf

And seem to say

Axle weights (from Mazda Europe):
Front: 950kg
Rear: 1250kg

So, if 95 is 690kg then multiplying that by 2 appears to give total safe weight of 1380kg which is safely over the Bongo axle weight if that figure is the gross (max permissible) axle weight (which i suspect it is as otherwise even the 96 rated tyre and its 710kg allowance would hardly allow for two medium/heavy front seat passengers). However, I'm not an expert on this so would welcome thoughts from techies like Rita, but it does seem like the 95 rated tyres might gain approval from insurers as safe if these calculations are offered to them.

[joeldrummer79]

Very interesting, I've been using this information quite a lot over the last few days, searching for the right tyres is frying my brain!

Anyway, I'm stuck at a bit of a crossroads at the minute. So, After searching for 225/55/17 and 225/50/17 I starting also searching for 215/55/17 but then it occurred to me that maybe I should completely downsize back to standard 15" and here's the reason why...

This is my first Bongo and my first vehicle larger than a car so at first I assumed that the way my Bongo drives is the way it is, but now I am not so sure. My Bongo tends to feel like a big "boat" on the road, particulary on corners, it tends to sort of "float" down the road and on corners, it feels really "eerie" round bends and you have to take it really slow, almost as if you feel you could easily roll it on a corner. This is the only way I can really describe it

Do Bongos normally feel like this or could this be down to the fact I have 17" alloys on as opposed to the standard 15" ??? Or could it be something else?

I'm wondering if putting 15" back on will improve it.

All of you guys that have larger wheels on, how has it affected your drive? I know efficiency and acceleration etc changes but how about handling and comfort etc?

Again, because I bought this van with 17" wheels already on I don't know about offsets and wheel dimensions etc so don't know about any modifications it has had to make these wheels fit so therefore, I don't know If I have to do any extra work to put 15" back on....

Could really do with some advice here...

On another note, My Bongo was successfully serviced other day with new timing belt, water pump, thermostat, aux and AC belts replaced as well as the usual oil and filter changes. He found two small coolant leaks which was sorted, complete coolant flush and bleed and a few advisories for me so I'm happy there and yesterday went to New Dawn Conversions and had Passenger and Drivers swivel seats fitted and I love them! Cheers Den!

[mikeonb4c]

Excellent about work done and presume they knew how to bleed a Bongo.

I have both 15"and 17" wheels and done a lot of miles on both. If anything the 17" wheels make the Bongo feel more planted on the road. Rider is perhaps v slightly harsher on rough roads with 17" wheels, maybe due to higher unsprung weight.

The Bongo is a narrow track top heavy (if AFT model - thats a lot of weight high up) vehicle and although the mid engine gives them nice balance in bends, they can't be taken through at same speeds as your average car due to the high C of G and softish suspension. A change of driving style and expectations might be needed but hey, we are supposed to be relaxing in a campervan ha ha. But i think some impatient drivers pull out of side turnings in front of me, hustle to overtake etc as they don't want to be stuck behind a campervan especially on bendy roads.

[joeldrummer79]

Excellent about work done and presume they knew how to bleed a Bongo.



I have both 15"and 17" wheels and done a lot of miles on both. If anything the 17" wheels make the Bongo feel more planted on the road. Rider is perhaps v slightly harsher on rough roads with 17" wheels, maybe due to higher unsprung weight.

The Bongo is a narrow track top heavy (if AFT model - thats a lot of weight high up) vehicle and although the mid engine gives them nice balance in bends, they can't be taken through at same speeds as your average car due to the high C of G and softish suspension. A change of driving style and expectations might be needed but hey, we are supposed to be relaxing in a campervan ha ha. But i think some impatient drivers pull out of side turnings in front of me, hustle to overtake etc as they don't want to be stuck behind a campervan especially on bendy roads.

Thanks Mike, you're very helpful

Yes I specifically showed him exactly how to bleed the Bongo haha.

Yes mines an AFT and understand that the higher centre of gravity means it has to be driven slower etc. Just wanted to make sure that its not the larger diameter wheels that make it feel a bit dodgy on corners etc. The suspension does feel very soft and almost "bouncy" so I'm assuming the way this motor drives is pretty normal.

My mechanic reckons theres very slight play in the front suspension bushes but nothing to worry about at this stage, after all, it passed its MOT only 2 months ago, I might look at getting that sorted next

Mike are your wheels 215/55/17 or 225/55/17? I'm thinking about clearance and amount of road contact and think one of your posts says you got 215/55/17. Would 225/55/17 actually fit in terms of clearance?

[Bob]

I have original steels and have to say it feels pretty solid when driving.

It might pay to at least get a passenger ride in another one for comparison.

Worst handling car I ever had I used to describe as 'Like driving a paving slab on four bed springs'.

1964 Vauxhall Velox, and I swore I'd never own another Vauxhall.

Haven't so far.

[mikeonb4c]

Mine are 215/55/17. I think 225 should fit but i'd ask a tyrefitting company before committing to buy, unless someone on here can advise.

[Tony x]

The wallowing / floating feeling isn't normal and will most likely be due to the damping in the shocks having gone. The £100 ish rear air suspension mod will help a lot although it masks rather than solves the issue.
Just a quick note on spare tyres. Once you know what size you need ( use the tyre size calculator ) save money and get a part worn one. It'll probably be a better size anyway as your originals will likely be worn if you get a puncture.

[mikeonb4c]

The wallowing / floating feeling isn't normal

Don't forget that an AFT with all that weight up top will be a different handling beast to a tintop, which is an altogether more sporty beast.

[Markas]

Mine are 215/50 R17 95V all round. I could do without changing them as they're pretty much new but I am concerned about the weight over the rear axle... It has a rear conversion and wheels do look pretty flat. That's a point actually, what should the tyre pressure be for this tyre/load and with a rear conversion? I've checked internet but cannot get a definitive answer!

I had a rear conversion fitted in my van this summer. Since that was done I've 'upped' the pressure in the rear tyres to 39psi with no ill effects in the handling department or on tyre wear and it looks about right. The tyres are more than capable of coping with the extra few psi. Caravan tyres typically are around 42psi to cope with the extra weight of fridge, cooker, heat source etc. which is placed over the axle.

[Bob]

Just for interest our caravan tyres run a 60 psi as called for in the handbook.