Putting larger wheels on MH

[spitfire]

Those running 16” rims, what tyre profiles are you running?

Dropping to 65’s with 16” rims would keep the diameter to within .1” of the original 15” with 70’s on.

Hence no real world difference......That is what I’d be doing.

We have just taken delivery of a new van with 16’’ . Came as a bonus as ordered the 15’’. Also came with air assist suspension for free also

 

[spitfire]

Not sure if it is useful or not but tyres fitted are 225/75 R 16 CP Michelin Agilis Camping

 

[peterc10]

I would not get to concerned about the potential loss of power and potential increase in fuel consumption as I have not noticed one iota of difference since fitting our 16" wheels last year.
As for the speedo reading, ours still reads higher that the actual road speed going by the satnav and dashcam which both show the same speed and I would trust to more accurate being GPS.

And when you fitted them Paul, did you adjust the Speedo? I have not heard of anybody doing it when upgrading tyre size.

 

[Two on Tour]

And when you fitted them Paul, did you adjust the Speedo? I have not heard of anybody doing it when upgrading tyre size.

No Peter, our speedo was read far higher than actual speed on the 15" and now on 16" it is more accurate but still reading higher.

 

[TheTwoOfUs]

I'm thinking of going up to 16" wheels for a couple of reasons, neither of which is cosmetic. The tow bar is very low and tends to catch the ground at the slightest change of incline ie ferry ramps, supermarket entrances abroad. So a change especially if kept at the same profile ratio will help. Secondly I'm fed up of the speedo being so inaccurate. Again this will help. Ride comfort should improve also. I believe unlike some that fuel consumption will actually improve. It should cruise comfortably at 60mph using lower revs which in turn means less fuel. And for those that say it will reduce the power, it won't. The engine produces the power at it's stated rating, it's the ability to transmit that power to the road that may change but seeing as it's designed to be able to move the vehicle forward at considerably more than the 60mph I do I don't think it will affect me.

^{_{Subscribers  do not see these advertisements}}

 

[Richard n Ann]

Maybe controversial.....I prefer the ride on 15” wheels, bigger tyre profile = smoother

Notinterested in aesthetics or handling when Im cruising in a van

Absolutely! A friend of mine has a transit with Carlos Fandangos on it and has to be VERY careful of potholes and curbs

 

[george w menzies]

most important thar wheels and tyres are matched to your vehicle maximum laden wieght.

 

[two]

15" or 16" are options on some motorhomes. I assume that no change is made to the base vehicle.
I don't think you'll get any significant difference but may imagine some. Sod will always make sure that whatever you'd like to clear is 1/2" higher than what you've got. The bigger wheels may look prettier, though.

 

[minesapint]

If you don’t reduce the tire height at the same time, the wheel will have a larger rolling circumference so your speedo will under read your speed.

A problem with reducing the tyre height is a low profile tyre may be more prone to damage if you go over a kerb or some junk in the road, also the ride height with a low profile tyre would not be improved.

 

[peterc10]

I never rely upon the speedo mainly because I can never read the bloody thing without squinting at it for 5 seconds because it is a X290 Ducato! The built in Gramin sat nav shows me (and the management) actual speed, and I have my phone set up to Sygic to also show actual speed and warn of cameras.

^{_{Subscribers  do not see these advertisements}}

 

[Clipgate]

Approval of original design has to be considered often overlooked, depends on the construction date and or approval of design. Plus notice to insurers may well be required as this is deemed a modification from standard.
Note form legislation giving dates: All motor caravans (also known as camper vans, motor homes, recreational vehicles) used on the road must comply with various rules about their construction. In addition, from April 29 2012, new motor caravans have been required to be approved. This means that a government agency will need to sanction the design of new motor caravans before sales can begin.

 

[DBK]

Talk of (seemingly) dramatic and adverse changes arising from a 16" diameter wheel begs the question, how do Fiat get away with it when they offer both 15" and 16" wheels on their vans?

You're surely not suggesting Fiat make all manner of changes to gearbox ratios, speedos and engine builds to compensate.

Or maybe they fit lower profile tyres to offset the change in wheel diameter?

The final drive ratio is different for 15" and 16" wheels. This is how they compensate.

The actual ratio varies between engines but on the 150 the ratios are:

4.933: 1 15" wheels
5.231: 1 16" wheels

 

[XxAnthxX]

A problem with reducing the tyre height is a low profile tyre may be more prone to damage if you go over a kerb or some junk in the road, also the ride height with a low profile tyre would not be improved.

Absolutely correct....I put 22” overfinch alloys on my T5 and the tyre walls were like elastic bands in an attempt to keep the rolling radius as close as possible to the original. I might as well of had steel banded cart wheels on it.

In my post I never mentioned ride height, comfort or damage, just facts relating to the change.

15" or 16" are options on some motorhomes. I assume that no change is made to the base vehicle.
I don't think you'll get any significant difference but may imagine some. Sod will always make sure that whatever you'd like to clear is 1/2" higher than what you've got. The bigger wheels may look prettier, though.

I have no idea what Fiat or worse still what converters do to compensate......but when car manufactures change wheel size they adjust the tyre size fitted to compensate, Maintaining clearance and diameter.

My post was to point out the physics of the change.....something you can argue all day but cannot change.

Have a play here to see what sizes are comparable and what differences changes will make.

Tire Size Comparison

Tire size comparison the easy way. Use our tire size comparison calculator to compare diameter, width, sidewall, circumference and revolutions per mile.

tiresize.com

As I mentioned earlier a 215 65 16 will have next to no difference over a 215 70 15......

No preferences expressed, just the facts.

 

[Paulypaul]

We replaced our 15" wheels for 16" and the speedo is spot on now rather than showing slow

 

[Oldgustaf]

Oh, I think I'm up for this. Anyone know where I can get a set of 16in alloys? For sale (soon): set of four 15in alloys and a steel spare. Tyres have done about 1,000 miles.

^{_{Subscribers  do not see these advertisements}}

 

[peterc10]

The final drive ratio is different for 15" and 16" wheels. This is how they compensate.

The actual ratio varies between engines but on the 150 the ratios are:

4.933: 1 15" wheels
5.231: 1 16" wheels

That can only apply to PVCs. Fiat will not know what wheels the converter will be putting on, especially with A class models which are destined to have Alko chassis added.

 

[Howard H]

Oh, I think I'm up for this. Anyone know where I can get a set of 16in alloys? For sale (soon): set of four 15in alloys and a steel spare. Tyres have done about 1,000 miles.

Tyresave in north wales 07831 365412 / 01244 813030 they advertise in MMM every month ,it’s where I got mine from via the internet and had no problems at all .

 

[DBK]

That can only apply to PVCs. Fiat will not know what wheels the converter will be putting on, especially with A class models which are destined to have Alko chassis added.

I guess the converters know what wheels they are going to fit so they order from Fiat a power train with the correct ratio final drive.

 

[TUCANO]

Pardon my ignorance here please, changing the rims from 15 to 16 also requires a tyre change yes

 

[Howard H]

Pardon my ignorance here please, changing the rims from 15 to 16 also requires a tyre change yes

Yes and if using alloy wheels from steel a change of wheel studs .

^{_{Subscribers  do not see these advertisements}}

 

[Landy Andy]

My Moho is offered with both size wheels.

So can run 215/70 R15
or 225/75 R16

Roof height on 15s is 2.78m and 16s is 2.8m.

 

[TUCANO]

I have had alloys fitted to my 'new to me' van and they are manufactured to take rhe same bolts as the OEM.
I did this also to a previous van and had no problems, same alloys but different size

 

[MobyDick57]

I changed our 215 70x15 to 225 65 x 16 on an Burstner ixeo it720, when upgrading the weight from 3500kg to 3850kg. There was a vast improvement in the handling, especially reducing the “wag” from other vehicles passing. I put the reason down to lower profile and especially due to the extra rubber on the road. I then uprated the rear spring suspension with a Dunlop air-assist unit. Then notified Vetech (I think that’s their name) who sent me an ok certificate, which I forwarded on to my insurance company. They seemed disinterested, however I am sure they would have been very interested if I had had an accident!

 

[bluesurf989]

Im going for these

 

[Howard H]

Im going for these

Nice

^{_{Subscribers  do not see these advertisements}}

 

[bluesurf989]

What do you think?

 

[Ian Bosman]

Vehicle speedometers are allowed to "over read" by upto 10% but never under read, so when doing an indicated say 70mph, you might actually only be doing 63mph and quite often going up a tyre size, be it a rim size or a aspect ratio quite often brings it closer towards a true reading

Speedos are allowed to be up to 10%fast, ie over reading so what you see as 30mph can be actually around 27mph. BUT, they are not allowed to under-read by any margin at all, part of the Construction and Use Regulations. This is so that whatever the speed you are doing your speedo will be giving you a higher reading. GPS are accurate but not infallible so be careful. I have a GPS speedo as the 2009 Ducato speedo is bad to read and my kit is digital just like I have on my 2015 Corsa. It can be set to display digital and a boon for driving at the correct speed but I usually drive with the the speed limiter setting to the speed limit which is one upgrade I would love to have on my Ducato

 

[tacr2man]

What do you think?

If the tread surface area isnt covered by the wheel arches its illegal . The second thing to consider is increased wear on wheel bearings due to leverage caused by off set of track , Third thing is more likelihood of wear on track rod ends . That should do for a start Good tyre choice

 

[XxAnthxX]

What do you think?

Go large or go home........

 

[Paul and Val]

Be very, very careful. Insurance companies will look for any excuse not to pay out.

You will be ok if the tyre size (which MUST be reduced in height to match the original tyre) is the same as one offered by FIAT BUT if it is a non-standard size you MUST consult your insurance company and get agreement in writing.

I would be very surprised if they would agree to a 'taller' tyre than standard being agreed to. They will take your money every year with a smile but in the event of an accident the first thing that is checked is the tyres.

^{_{Subscribers  do not see these advertisements}}