Cooper Discoverer AT3s
- Thread starter andrewga
- Start date
So after a lot of reading on this forum and others to figure out what I was doing I splashed out on some new wheels and tyres. Huge thanks to everyone for amassing such a huge library of information. Here's my very brief summary of what worked for me, based on the following threads:
Useful threads on this forum:
- General Information - Wheels & Tyres to figure out what all the numbers and sizes meant
- All-Season Tyre recommendations to see what people were doing and getting feedback on different tyres
- Show us your 17s to get the right 'look' that I was after
I decided on the following set up:
Couple of points I deliberated over a lot:
Impact of having bigger outside diameter:
I started off with the standard 215/65/16 6.5J wheels that came on my T32 17 years ago
. I always felt they looked too small, so I wanted to go bigger but wasn't sure what would rub, and I wasn't sure if this was going to impact the acceleration/performance/reliability of the van. It seems that as long as you have a decent offset (-30 or -40 seem popular) you can get away with 245/65/17 and lots of people buy BFGs at this size. The performance was more of a concern for me, as I do tow a caravan and trailers. Using the amazingly useful tyresize calculator at willtheyfit.com it showed that 245/65/17s have a speedo error of 9% (i.e. for every rotation of the wheel the van goes 9% faster/further and I felt that this was a bit too much for me to take a chance on. Others have done this and not reported problems, but I felt that going down to 235/65/17 with 7% error would save me a little torque. These ended up 2 inches diameter bigger than the originals, so the van site 1 inch higher than it did before on standard suspension. After driving my 2006 2.5l 6-speed 130bhp on these for a week I can confidently say I don't feel like I've lost acceleration or that the van is labouring at all. Some people go for 235/55/17s, but I went for 65 as I think the extra rubber softens the bumps on our rubbish road surfaces.
How much 'poke' is too much?
This confused me for a bit, as most ET offsets are minus numbers, and the more 'minus' it gets the less the wheels stick out. The willtheyfit.com calculator makes it very simple though. I put a straight edge across my old wheels and measured how far this was inside the wheel arch (as I didn't want to be failing my MOT for protruding tyres!) - I had 40mm at the front and 45mm at the back, so with my new setup coming out 37mm more I should have been pretty close. I ordered some 5mm spacers for the back to bring them out more. In reality when I got them on the van the front looks perfect but the back could have done with a 10mm or maybe even a 15mm spacer. Maybe an upgrade for another day!
How noisy/uncomfortable will they be?
This was very important for me. The van is my main family vehicle and I do a lot of driving with the family. My number 1 reason for not going for BF Goodrich ATs was noise, and lots of people have said that they make a lot more noise. There are better noise reports from the General Grabbers, and better from the Pirelli Scorpions, but I just didn't like the look of these. I have to say I am VERY pleased with the Coopers. Even though they look like a reasonable aggressive AT tyre they are very comfortable. Up to 40mph there is significantly less than the cheapie van tres I had on before. Above 40mph there is a bit of a low rumble, bit it's not very noticeable at all.
Grip and braking in the wet
There are a lot of differing opinions on this, so this is just my feelings. One of the key aspects that allows a road tyre to have grip in the wet is the channels that run around the circumference of the tyres through the thread pattern that help to channel away water (see here). Now imagine a BFG tyre thread pattern going through the water - where is the water going to flow? A good off-road tyre is designed to grip the mud and push it, not make it flow out of the way, so off-road performance and on-road wet traction are always going to be opposite ends of the scale. For me one of the best features of the Coopers is that they have a good thread pattern for getting rid of water. And they look cool! I haven't tested this yet though...
White sidewall writing
This was a look I wanted. I know I could have it with BFGs, but I didn't want them due to noise and wet grip performance. Sometimes you have get Grabbers with white sidewalls, but this seems hard to do. It should be as simple as adding OWL (outline white lettering) or RWL (raised white lettering) to the tyre code, but my local tyre places wouldn't guarantee it. And I know you can get tyre pens and colour it in yourself. However Cooper have a really clear chart on their site that shows which sizes actually have white lettering and which don't. It works for me.
So that's my thoughts on this setup. I'm really pleased with the look, fit and comfort.
Happy modding!
Useful threads on this forum:
- General Information - Wheels & Tyres to figure out what all the numbers and sizes meant
- All-Season Tyre recommendations to see what people were doing and getting feedback on different tyres
- Show us your 17s to get the right 'look' that I was after
I decided on the following set up:
- Tomahawk Outlaw 17s
- 8j (i.e. 8 inches wide) - this is the only option for these wheels but seems to be about what most go for
- ET35 - i.e. an offset of -35mm, giving 37mm more 'poke' i.e. the rims stick out 37mm more than the standard wheels
- Load rated at 1250kg each, which is loads more than the 860kg each needed for a T32 (see here for numbers)
- Bought from Performance Alloys for £700 delivered. Awesome service, quick delivery. Could not recommend more highly! Plus they are a UK / Northern Ireland company so it's good to support local
- Cooper Discoverer AT3 Sport 2 tyres
- 235/65/17
- £648, special order fitted at my local tyre place - support local where you can
- 737mm outside diameter (calculated on www.willtheyfit.com)
- 7% speedo error
- Load rating 108 (only needed 106 for my T32 at this size). The load rating varies with the tyre dimensions. Check the plaque on your drivers door pillar for your van's requirements
- Speed rating T (rated to 118mph, see The AA guide)
- White sidewall lettering - this was important to me!!
Couple of points I deliberated over a lot:
Impact of having bigger outside diameter:
I started off with the standard 215/65/16 6.5J wheels that came on my T32 17 years ago
. I always felt they looked too small, so I wanted to go bigger but wasn't sure what would rub, and I wasn't sure if this was going to impact the acceleration/performance/reliability of the van. It seems that as long as you have a decent offset (-30 or -40 seem popular) you can get away with 245/65/17 and lots of people buy BFGs at this size. The performance was more of a concern for me, as I do tow a caravan and trailers. Using the amazingly useful tyresize calculator at willtheyfit.com it showed that 245/65/17s have a speedo error of 9% (i.e. for every rotation of the wheel the van goes 9% faster/further and I felt that this was a bit too much for me to take a chance on. Others have done this and not reported problems, but I felt that going down to 235/65/17 with 7% error would save me a little torque. These ended up 2 inches diameter bigger than the originals, so the van site 1 inch higher than it did before on standard suspension. After driving my 2006 2.5l 6-speed 130bhp on these for a week I can confidently say I don't feel like I've lost acceleration or that the van is labouring at all. Some people go for 235/55/17s, but I went for 65 as I think the extra rubber softens the bumps on our rubbish road surfaces.How much 'poke' is too much?
This confused me for a bit, as most ET offsets are minus numbers, and the more 'minus' it gets the less the wheels stick out. The willtheyfit.com calculator makes it very simple though. I put a straight edge across my old wheels and measured how far this was inside the wheel arch (as I didn't want to be failing my MOT for protruding tyres!) - I had 40mm at the front and 45mm at the back, so with my new setup coming out 37mm more I should have been pretty close. I ordered some 5mm spacers for the back to bring them out more. In reality when I got them on the van the front looks perfect but the back could have done with a 10mm or maybe even a 15mm spacer. Maybe an upgrade for another day!
How noisy/uncomfortable will they be?
This was very important for me. The van is my main family vehicle and I do a lot of driving with the family. My number 1 reason for not going for BF Goodrich ATs was noise, and lots of people have said that they make a lot more noise. There are better noise reports from the General Grabbers, and better from the Pirelli Scorpions, but I just didn't like the look of these. I have to say I am VERY pleased with the Coopers. Even though they look like a reasonable aggressive AT tyre they are very comfortable. Up to 40mph there is significantly less than the cheapie van tres I had on before. Above 40mph there is a bit of a low rumble, bit it's not very noticeable at all.
Grip and braking in the wet
There are a lot of differing opinions on this, so this is just my feelings. One of the key aspects that allows a road tyre to have grip in the wet is the channels that run around the circumference of the tyres through the thread pattern that help to channel away water (see here). Now imagine a BFG tyre thread pattern going through the water - where is the water going to flow? A good off-road tyre is designed to grip the mud and push it, not make it flow out of the way, so off-road performance and on-road wet traction are always going to be opposite ends of the scale. For me one of the best features of the Coopers is that they have a good thread pattern for getting rid of water. And they look cool! I haven't tested this yet though...
White sidewall writing
This was a look I wanted. I know I could have it with BFGs, but I didn't want them due to noise and wet grip performance. Sometimes you have get Grabbers with white sidewalls, but this seems hard to do. It should be as simple as adding OWL (outline white lettering) or RWL (raised white lettering) to the tyre code, but my local tyre places wouldn't guarantee it. And I know you can get tyre pens and colour it in yourself. However Cooper have a really clear chart on their site that shows which sizes actually have white lettering and which don't. It works for me.
So that's my thoughts on this setup. I'm really pleased with the look, fit and comfort.
Happy modding!
D
Deleted member 50124
Guest
Excellent post. Thanks so much for spending the time!So after a lot of reading on this forum and others to figure out what I was doing I splashed out on some new wheels and tyres. Huge thanks to everyone for amassing such a huge library of information. Here's my very brief summary of what worked for me, based on the following threads:
Useful threads on this forum:
- General Information - Wheels & Tyres to figure out what all the numbers and sizes meant
- All-Season Tyre recommendations to see what people were doing and getting feedback on different tyres
- Show us your 17s to get the right 'look' that I was after
I decided on the following set up:
- Tomahawk Outlaw 17s
- 8j (i.e. 8 inches wide) - this is the only option for these wheels but seems to be about what most go for
- ET35 - i.e. an offset of -35mm, giving 37mm more 'poke' i.e. the rims stick out 37mm more than the standard wheels
- Load rated at 1250kg each, which is loads more than the 860kg each needed for a T32 (see here for numbers)
- Bought from Performance Alloys for £700 delivered. Awesome service, quick delivery. Could not recommend more highly! Plus they are a UK / Northern Ireland company so it's good to support local
- Cooper Discoverer AT3 Sport 2 tyres
- 235/65/17
- £648, special order fitted at my local tyre place - support local where you can
- 737mm outside diameter (calculated on www.willtheyfit.com)
- 7% speedo error
- Load rating 108 (only needed 106 for my T32 at this size). The load rating varies with the tyre dimensions. Check the plaque on your drivers door pillar for your van's requirements
- Speed rating T (rated to 118mph, see The AA guide)
- White sidewall lettering - this was important to me!!
Couple of points I deliberated over a lot:
Impact of having bigger outside diameter:
I started off with the standard 215/65/16 6.5J wheels that came on my T32 17 years ago
How much 'poke' is too much?
This confused me for a bit, as most ET offsets are minus numbers, and the more 'minus' it gets the less the wheels stick out. The willtheyfit.com calculator makes it very simple though. I put a straight edge across my old wheels and measured how far this was inside the wheel arch (as I didn't want to be failing my MOT for protruding tyres!) - I had 40mm at the front and 45mm at the back, so with my new setup coming out 37mm more I should have been pretty close. I ordered some 5mm spacers for the back to bring them out more. In reality when I got them on the van the front looks perfect but the back could have done with a 10mm or maybe even a 15mm spacer. Maybe an upgrade for another day!
How noisy/uncomfortable will they be?
This was very important for me. The van is my main family vehicle and I do a lot of driving with the family. My number 1 reason for not going for BF Goodrich ATs was noise, and lots of people have said that they make a lot more noise. There are better noise reports from the General Grabbers, and better from the Pirelli Scorpions, but I just didn't like the look of these. I have to say I am VERY pleased with the Coopers. Even though they look like a reasonable aggressive AT tyre they are very comfortable. Up to 40mph there is significantly less than the cheapie van tres I had on before. Above 40mph there is a bit of a low rumble, bit it's not very noticeable at all.
Grip and braking in the wet
There are a lot of differing opinions on this, so this is just my feelings. One of the key aspects that allows a road tyre to have grip in the wet is the channels that run around the circumference of the tyres through the thread pattern that help to channel away water (see here). Now imagine a BFG tyre thread pattern going through the water - where is the water going to flow? A good off-road tyre is designed to grip the mud and push it, not make it flow out of the way, so off-road performance and on-road wet traction are always going to be opposite ends of the scale. For me one of the best features of the Coopers is that they have a good thread pattern for getting rid of water. And they look cool! I haven't tested this yet though...
White sidewall writing
This was a look I wanted. I know I could have it with BFGs, but I didn't want them due to noise and wet grip performance. Sometimes you have get Grabbers with white sidewalls, but this seems hard to do. It should be as simple as adding OWL (outline white lettering) or RWL (raised white lettering) to the tyre code, but my local tyre places wouldn't guarantee it. And I know you can get tyre pens and colour it in yourself. However Cooper have a really clear chart on their site that shows which sizes actually have white lettering and which don't. It works for me.
So that's my thoughts on this setup. I'm really pleased with the look, fit and comfort.
Happy modding!
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My main concern is spacers. They are illegal in Australia, are they required for your wheels to work?
I feel like spacers wouldn't be great for wheel bearings either?
Spacers aren't required. I just wanted to bring the rear wheels out a little so that they looked the same as the front ones.
When it comes to wheel bearings, spacers are only part of the change. As you can see in the image below the larger (new) wheel has its centreline significantly further out that the original (smaller) wheel. With no spacer the wheel is already 37mm further out at the outer edge, so I figured another 5mm wouldn't make a big difference. When I was looking in to all this at the start I was more concerned about it impacting the geometry of the steering, but nobody seems to have issues that they are sharing about this!
However, you need to be very careful with spacers. The centre of the wheel must mount snugly on the spigot protruding from the hub. If you use a flat spacer and the inside of your wheel has a chamfer on it then you might not have much or any of the wheel centred on the spigot. This would cause the wheel to be slightly off centre and could cause massive vibration problems. Thinker spacers have their own spigot ring machined in to them, but then you're getting in to different bolts, etc.
When it comes to wheel bearings, spacers are only part of the change. As you can see in the image below the larger (new) wheel has its centreline significantly further out that the original (smaller) wheel. With no spacer the wheel is already 37mm further out at the outer edge, so I figured another 5mm wouldn't make a big difference. When I was looking in to all this at the start I was more concerned about it impacting the geometry of the steering, but nobody seems to have issues that they are sharing about this!
However, you need to be very careful with spacers. The centre of the wheel must mount snugly on the spigot protruding from the hub. If you use a flat spacer and the inside of your wheel has a chamfer on it then you might not have much or any of the wheel centred on the spigot. This would cause the wheel to be slightly off centre and could cause massive vibration problems. Thinker spacers have their own spigot ring machined in to them, but then you're getting in to different bolts, etc.
