7.5x16 to 235/85 tyres. Help for a newbie

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olydickens

Member
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24
Hi all, sorry to open this topic again, it's well documented I know.

On my 07 defender I have the original Michelin 7.5x16 on 5.5 steels. They will need replacing soon and I'm looking at a set of bf AT 235/85 as these are close to the originals which I like the height and look of. I've read that they will go on a 5.5 wheel but not be safe. Also as there approx an inch wider will I need spacers? Or if I buy a package (such as sold by paddocks) what offset should I be looking for (if any).

Thanks and sorry again guys
 
I recently did the same but got the 235/85 on steel modulars which i believe are 7j. No spacers or changes to stops needed as the offset puts the inside wall in same position as before. Makes the truck look a lot beefier too
 
I also changed mine about two/three years ago. I too fitted them on steel modular wheels. I found I was able to adjust the steering stops which then gave me a much better turning circle. My original 5.5 steels where for inner tube tires so I had to change the wheels for tubeless . I'm not impressed with the modular steel wheels. They are only a couple of years old and have already rusted. If I was doing it again I would look for something a bit better than Modular's
 
Hi all, sorry to open this topic again, it's well documented I know.

On my 07 defender I have the original Michelin 7.5x16 on 5.5 steels. They will need replacing soon and I'm looking at a set of bf AT 235/85 as these are close to the originals which I like the height and look of. I've read that they will go on a 5.5 wheel but not be safe. Also as there approx an inch wider will I need spacers? Or if I buy a package (such as sold by paddocks) what offset should I be looking for (if any).

Thanks and sorry again guys

Hi.

First up, there is a quite a lot to learn here. And honestly, it would be well worth you putting in the effort to understand it all. It'll make you a rare thing then, an 'informed buyer'. But at least you'll know what you are getting and understand that it is the right thing.



To help you out.

You can still get 7.50 16 tyres. OK the choice isn't as varied and you might have to hunt them down. But it is still a viable option. But does depend a little on what type of tyre you are after.

The only downside is, some tyre makers are a little dishonest when it comes to 7.50's and they will simply brand a 235/85R16 as a 7.50

The thing is, while they are similar, these two sizes really aren't the same. A proper 7.50 should be very narrow. 7.50" in fact. A 235 is 235mm wide or 9.25", so a fair bit wider. Height wise, again similar, but there is a lot of variation in height for 7.50's, so this is less of an issue.


Technically, most 235/85R16 tyres require a 6j rim as a minimum. In reality you are probably perfectly fine fitting them to a 5.5j rim, but it's a matter of legality. Technically it is illegal and should you be in an accident and someone spot this, then it could cause you issues.

The fact that many remould 7.50's are indeed 235's with a different sidewall stamp on, really doesn't help, as you could then legally run the same width tyre on a 5.5j rim. Bit stupid, but this bit isn't regulated, so it is what it is.



As for offset. Standard LR 5.5j rims are not only narrow, but also sit quite far inside the arches, i.e. make the track narrower. With narrow tyres this isn't an issue as you can still get enough steering lock.

Fit wider tyres and they may rub the radius arms on full lock. Not really a major issue, but it will increase your turning circle.

Most aftermaret rims and other LR Defender rims will sit the wheels more outboard, i.e. make the track wider. This is to give more room to get full lock on wider tyres.


If you are looking at some new rims. Then you have a huge choice. Common aftermarket steels are the 8 spoke or Modular design. Available in many sizes and offsets. Land Rover also offer the Wolf rims and there are cheaper aftermarket copies of them too.

For a standard'ish sized tyre, any will likely be fine.


A 16x8 or 16x7 size rim will be ideal and allow a reasonable choice of sizes to be fitted. Standard LR sizes for the Defender are usually 235/85R16 or 265/75R16. The latter is a little fatter and not quite as tall. But both work fine.

In terms of offset. If you go for a deep dish set of rims, it'll move the wheels even further outbound. This can often give them a nice stance. And allow you to wind in the steering stops and give you a much better turning circle.

However wide tyres may then stick out of the arches, which is illegal under Construction & Use Regs. And more likely to throw more mud up the side of the vehicle.

A 235/85 on some deep dish rims can work well however. Deep dish rims for a Defender will have a negative ET offset, such as ET-25. Anything with a positive offset such as ET08 or ET25 won't stick out as far.



Not the easiest photo to see this. But this Landy has different offset rims front and rear.


The rear stick further in, while the fronts stick further out. This gives it a better turning circle, without the need for the rear wheels to stick out as much.

Both of these rims stick out a lot further than standard LR rims.
 
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Thanks so much for such an indepth answer and taking the time to.write it. Seems alot simpler than I thought
 
Devon 4x4 seem responsible for wheel prices, think I'll go for the white eight spoke 16x7 as I've a white roof and like the matching shirt and shoes :) I'll shop around for tyre, either bf AT or continental cross AT
 
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