Alternative Wheel Question

[Torvil]

Has anyone changed their wheels who could offer advice please?
I have a Hymer A class with standard 15" wheels
shod with 215
70 15 tyres. I want to change the wheels as they are badly oxidised from being diamond cut, refurbished only three years ago from the centre hub outwards. All four wheels have gone and shame. The rest of the vehicle. To aid traction I am wanting to fit 225 75 16 tyres on 16"rims. The other advantage is the extra rolling circumfirance I think will enable the speedometer to truly reflect the speed as currently it's reading as much as 10% faster than it is actually travelling.
I am looking to fit 16" wheels with circa ET50 off set and as I have a lightweight Alko chassis, I am restricted to PCD fitment 118 which appear rarer than 130 PCD. I know about weight rating so anything with 1250kg allowance will be fine. Has anyone any experience/advice/suggestions they can offer please?

 

[Bill-H]

There is a size comparison chart you can input all the combinations of sizes available, then look at the results.

Tire Size Calculator

Free calculator to find the dimensions of a tire based on its code. It also helps in choosing alternative tire sizes based on rim size or comparing two tires.

www.calculator.net

 

[Guigsy]

On the question of selling on my 15” alloys with a correct description, would anyone know how I can
tell if these are ‘diamond cut’ or otherwise?

Diamond cut is just the cosmetic finish where the alloy is first painted and then the face is machined off to bare metal and then lacquered. It's fashionable. And it's also not very durable. The lacquer fails and the bare metal underneath corrodes.

No, I don't think those are diamond cut.

 

[Happy Jack]

Tire Size Calculator

Free calculator to find the dimensions of a tire based on its code. It also helps in choosing alternative tire sizes based on rim size or comparing two tires.

www.calculator.net

Yes that's the one on tyre size.com that I said.
Maybe I should start putting links on.

 

[Landy Andy]

Dampers damp the movement between the unsprung wheels and the rest of the suspended body. If the wheels weigh more, dampers will have less effect. So you've hit a big pothole and the wheel is shuddering from the impact, you'll feel it more.

No. A bigger wheel and tyre will shudder less from the same impact as a smaller wheel. Off road vehicles use big wheels and tyres for a reason. A bigger haevier wheel. Smoother ride.

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[Guigsy]

No. A bigger wheel and tyre will shudder less from the same impact as a smaller wheel. Off road vehicles use big wheels and tyres for a reason. A bigger haevier wheel. Smoother ride.

They don't use heavy wheels to improve comfort. It's purely because they end up being heavy when they are that large for getting over terrain. And even then, they need to considerably up-size to make a significant difference.

Back to the point... The main reason for ride improvement was more down to putting good tyres on. Many people have switched just the tyres to achieve large comfort benefits. Changing the rim probably did very little.

 

[Lenny HB]

Normally alloy wheels are approx 30% lighter than

Not on Motorhome or van wheels, if you are lucky they will be 1 or 2kg lighter sometimes heavier.

I’m still wondering about the change from 15” to16” wheels and have to decide in the next couple of months, as the tyres on our MH will be seven years old and are starting to show their age. You’ve reminded me of a query I have…

… On the question of selling on my 15” alloys with a correct description, would anyone know how I can
tell if these are ‘diamond cut’ or otherwise? Having bought our MH used, we never got to see the original spec, or even if the wheels we have are/were standard… this is the wheel…

View attachment 1040189

Those are standard alloy not diamond cut.
This is a diamond cut wheel.

 

[Landy Andy]

They don't use heavy wheels to improve comfort. It's purely because they end up being heavy when they are that large for getting over terrain. And even then, they need to considerably up-size to make a significant difference.

They don’t fit lighter wheels for comfort. They are happy to have heavier wheel, as is stronger, and more stable.

Try riding a bromtom bike up a pot holed road and then try riding a 29r up the same road. The ride will be far smoother with the 29” wheel. Nothing to do with weight. Bigger wheel smoother ride.

 

[Guigsy]

They don’t fit lighter wheels for comfort. They are happy to have heavier wheel, as is stronger, and more stable.

Try riding a bromtom bike up a pot holed road and then try riding a 29r up the same road. The ride will be far smoother with the 29” wheel. Nothing to do with weight. Bigger wheel smoother ride.

I've got a Brompton and a 29'er. I bet my enduro bike would feel a lot rougher on 25mm tyres at 100psi. Tyres made the big difference, not rim size.

 

[Lenny HB]

ry riding a bromtom bike up a pot holed road and then try riding a 29r up the same road. The ride will be far smoother with the 29” wheel. Nothing to do with weight. Bigger wheel smoother ride.

Doesn't work with cars when they fit rubber bands for tyres on bigger wheels.

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[Landy Andy]

I've got a Brompton and a 29'er. I bet my enduro bike would feel a lot rougher on 25mm tyres at 100psi. Tyres made the big difference, not rim size.

And your bromton with100psi in the tyres would be worse than your enduro. A bigger diameter will, roll easier across rough ground.

 

[Landy Andy]

Doesn't work with cars when they fit rubber bands for tyres on bigger wheels.

Unlike many, he isn’t swapping small wheels with big sidewalls, he’s swapping to bigger wheels and bigger sidewalls.

The op is looking at fitting 225/75/16, instead of their current 215/70/15

This will give
A tyre diameter increase of 8.9%
An an increase of tyre sidewall of 11.9%

This will make his drive dramatically better and softer, also increasing his ground clearance.

 

[Guigsy]

What’s 100psi got to do with it. A bigger diameter will, roll easier across rough ground.

It will. But the difference between a 15" and a 16" isn't much. Particularly when you're talking about road chatter sized roughness at 60mph and not rock gardens.

My Brompton's tyres are 100psi. My mountain bike is 19psi. I suspect a lot of the Brommie's harshness is down to the skinny tyres that have to be run concrete hard.

 

[Happy Jack]

Unlike many, he isn’t swapping small wheels with big sidewalls, he’s swapping to bigger wheels and bigger sidewalls.

The op is looking at fitting 225/75/16, instead of their current 215/70/15

This will give
A tyre diameter increase of 8.9%
An an increase of tyre sidewall of 11.9%

This will make his drive dramatically better and softer, also increasing his ground clearance.

Ride height will be approx 1" higher.