285 on 7"

[krt005]

Most 285/75 tire spec state that the minimum rim width should be 7.5". However, i have seen a couple of defenders with such tyres on boost alloys (which is 7"). So i was wondering how strict this spec is and what are the risks of using 285/75 tyres on boost (or other 7") rims.

2nd and more important question, will the difference between "standard" 265 vs 285 significantly improve handling?

Thanks

[BogMonster]

1) in practice it will be fine, the only potential issues would be anybody who wants to be snotty i.e. MOT men and insurers in the event of an accident who want an excuse to be difficult and/or relieve themselves of any liability!

2) probably not much difference I wouldn't think - though couldn't be sure. What are you calling "handling"? The 285s are an inch taller so will raise the vehicle's centre of gravity thus possibly making it handle worse, while the extra width might or might not improve grip on road.

[krt005]

Thanks for your reply.

Yes, by handling i mean grip. I'm actually looking for a 285 because i prefer the higher gearing from a taller tyre. I believe a td5 can very well cope with the extra torque needed.

[Mack]

I have the 285 on std 7" alloy and typical wheel spacers. However I ordered a set of Allied 8" wheels for safety reasons

[Ex Member]

7" is perfectly fine. You lose a bit of road handling, but you will hold a bead better off road.

These are 285 SSRs on 7" modulars.

[Michele]

Ditto.

I ran the same tires on 7" rims for a couple of years or more with no issue.

Only last year I had them fitted on 8" wide rims, they look better but no macroscopic difference as far as I can tell.

They sap power the same way

Here's mine with the SSRs and the 8" modulars.

P.S.

Sorry I forgot to resize the pic...

[Ex Member]

Michele, did you are can you measure the backspacing (or the fontspacing as it is easier) on the 8" modulars? They don't seem to stick out any further than the 7". Thanks, John

[Michele]

Yup, I just hope you're not in a hurry though...

[Ex Member]

No hurry. Just out of interest really. It would be nice if someone measured and published data for the various wheels available.

[Michele]

I agree...BTW I have an old data sheet I saved years ago which gathers the most common LR wheels.

It's in a folder, somewhere in my memory stick.

I'll sort it out and send over to you if you want to add rims to the springs page.

It's in German though, I need my sister to translate it.

As to my Modulars, I mean I won't be able to do that before next week

[Ex Member]

OK, cool. You provide data, I can make a webpage... No problemo.

If anyone else wants to help.... and you have a rim sitting around, please measure backspacing as a minimum. Frontpsacing would be good as well. There is a LOT of confusion over the terms. For this conversation, we will use this picture and not argue about terminology.

[Part1cle]

I thought rim width was measured between the flanges - where the bead of the tyre sits. There can be quite a difference in alloy and steel wheels when measured over the outside of the wheel and where the tyre bead sits and all other dimensions are taken from the inside of the flange also.

Never the less, well done for putting a piccy up on this, it will be really helpful to lots, I'm sure. I'll go out tomorrow evening and measure my standard Disco steels and some LR cyclone alloys.

Cheers, Henry.

[Ex Member]

Yes, rim width is inside between the bead surfaces. Rim width is not shown on the drawing above.

Back and front spacing is easy to measure and of most use for clearance issues.

Wheel width is less than the sum of back and front spacing, usually by around 1".

[Ex Member]

I'll start

NRC7578 (Defender tube rims)

16 x 5.5

Backspacing 110 mm (5")

Frontspacing 55 mm (2-3/16")

Offset 36 mm calculated (33 stamped on the rim)

Modular (unknown origin)

16 x 7

Backspacing 127 mm (4-5/16")

Frontspacing 97 mm (3-13/16")

Offset 15 mm calculated

[Ex Member]

Page started

http://members.shaw.ca/red90/roverwheels.html

[SteveG]

You may have a problem with modulars as I've found that all are not the same. There seems to be 7 & 8" versions with different backspacing in circulation.

IIRC backspace on the 8" modulars I had were about 4 1/4" and Wolf tubeless were about the same. Not accurate enough for your table and I don't have either rims anymore to measure for you.

However, if you put request on Int'l forum I'm sure you'll get plenty of replies and fill out the table soon enough.

I do have 16" Boost alloys, 18" Hurricanes and 18" LR specials on hand to measure though if you want these?

Have you thought about adding pics to table (if possible) with wheels I think it helps for people to see style to know what it is.

Cheers

Steve

[nicks90]

You may have a problem with modulars as I've found that all are not the same. There seems to be 7 & 8" versions with different backspacing in circulation.

same with 8 spokes,

there's a couple of varieties of 6.5" with differing backspace, same with 7" versions. I think there are 3 different ones in this width,

then you have the 8" 8 spokes and they have 2 differing backspaces too.

Lots of missinformation about on what to look for in wheels, its the BACKSPACE thats the important bit. No point thinking something with a good offset will work to reduce rubbing if its 2" wider than the wheels you had before - as the backspace may actually be worse and cause even more rubbing!

Minimal backspace means less rubbing.

[BogMonster]

OK, cool. You provide data, I can make a webpage... No problemo.

If anyone else wants to help.... and you have a rim sitting around, please measure backspacing as a minimum. Frontpsacing would be good as well. There is a LOT of confusion over the terms. For this conversation, we will use this picture and not argue about terminology.

[whining pedant]

I thought it was "kerb"...

[/whining pedant]

Seriously, great idea for a web page, there are sooo many different wheels around it would be good to have a page with as much data as possible

[Ex Member]

Yep, I'll link to pictures for each wheel, where possible.

I realize there may be a variety.... I'll do what I can to clarify. It is too bad that the aftermarket wheels are not marked at all. If you know where they were purchased, or have any more information, let me know. More information is better than less.

[Ex Member]

I see, I had some dyslexia last night... Try again as you can't edit old posts.

NRC7578 (Defender tube rims)

16 x 5.5

Backspacing 127 mm (5")

Frontspacing 55 mm (2-3/16")

Offset 36 mm calculated (33 stamped on the rim)

Modular (unknown origin)

16 x 7

Backspacing 110 mm (4-5/16")

Frontspacing 97 mm (3-13/16")

Offset 7 mm calculated

If you send information for the P38 bolt pattern, please say so... Otherwise I assume Rover 5 on 6.5".

[Mack]

Land Rover Alloys: they are 16x7" rims with 5.375" backspacing (1 7/8" offset to

the inside)

[Ex Member]

Land Rover Alloys: they are 16x7" rims with 5.375" backspacing (1 7/8" offset to

the inside)

Thanks. Which model in particular? Do you have the part number?

If there is a moderator watching, would you mind splitting off the tyre size discussion and moving it to the international forum? I've kind of hijacked the thread...

[LR90]

Not mine but I keep going back to it:

[BogMonster]

Thanks. Which model in particular? Do you have the part number?

Not 100% on this but I believe all the recent LR Defender/Discovery genuine 7x16 alloys have the same offset (i.e. Freestyle/Tornado, Deep Dish, Boost) and whatever it is, it is also the same as the 7x16 Discovery steel rims that were for some time used as a cheap spare wheel on Tdi Discoverys.

[Ex Member]

I thought most Disco wheel had a 33mm offset. The number listed above is 48 mm??