Tyre sizes

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Discussion

100SRV

Original Poster:

2,179 posts

249 months

Thursday 20th January 2022
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Looking at the 16" rim options for the BF Goodrich KM3 I noticed that it is available as:

7.50 100 R 16
235/85 R 16

Which as I understand are pretty much the same rolling radius.

Why would two similar sizes be offered - both are radial ply so it can't be that.

camel_landy

5,084 posts

190 months

Thursday 20th January 2022
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IIRC - It's to do with the width... I believe the 7.50 will be a touch narrower.

M

100SRV

Original Poster:

2,179 posts

249 months

Friday 21st January 2022
quotequote all
camel_landy said:
IIRC - It's to do with the width... I believe the 7.50 will be a touch narrower.

M
I thought the same, still a funny thing to do but guess it is good for older non-PAS vehicles like Series Land-Rovers and Jeeps.

camel_landy

5,084 posts

190 months

Friday 21st January 2022
quotequote all
100SRV said:
I thought the same, still a funny thing to do but guess it is good for older non-PAS vehicles like Series Land-Rovers and Jeeps.
It's also why the XZLs on my 110 are 7.50R16 XZLs, instead of 235/85R16 (ie narrower).

M

100SRV

Original Poster:

2,179 posts

249 months

Friday 21st January 2022
quotequote all
camel_landy said:
100SRV said:
I thought the same, still a funny thing to do but guess it is good for older non-PAS vehicles like Series Land-Rovers and Jeeps.
It's also why the XZLs on my 110 are 7.50R16 XZLs, instead of 235/85R16 (ie narrower).

M
Different tread pattern too wth the two XZL sizes, 7.5 has single centre blocks and 235 twin.

300bhp/ton

41,030 posts

197 months

Wednesday 30th March 2022
quotequote all
100SRV said:
Looking at the 16" rim options for the BF Goodrich KM3 I noticed that it is available as:

7.50 100 R 16
235/85 R 16

Which as I understand are pretty much the same rolling radius.

Why would two similar sizes be offered - both are radial ply so it can't be that.
7.50 x 16 is a very nice size. In theory they should have 7.5" section width and 7.5" side wall for a total height of 31". Although they are often a fraction over in reality.

A 235/85R16 is similar, but fatter. As 235mm = 9.25" the sidewall is also 85% of the section, so 7.7" tall.

Differences in real world. The 7.50 will fit a narrower rim, such as a standard Series II or III Land Rover rim, where the 235/85 is technically not rated for a 5.5j rim.

The 7.50 probably weighs less. And IMO narrower tyres tend to work better off road in the UK.

If it were me. I'd opt for 7.50 x 16 out of the two sizes.

camel_landy

5,084 posts

190 months

Wednesday 30th March 2022
quotequote all
300bhp/ton said:
And IMO narrower tyres tend to work better off road in the UK.

If it were me. I'd opt for 7.50 x 16 out of the two sizes.
Agreed

M

100SRV

Original Poster:

2,179 posts

249 months

Monday 4th April 2022
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Had a set of 7.5 R 16 XZLs on 5.5" Land-Rover rims, can't think why but they were sold to a friend who had an 86" so my Dad's 88" now has 235/85R16 XZLs on the Defender HD rims. I'll ask the guy with the 86" to measure the width at the tread face of the 7.5 tyres so we've got some facts. The 7.5" wide ones only had three lugs across the tread face, the 235's having four.

Here it is on the 235s, I'll see if I can find one of in on the 7.5s


Edited by 100SRV on Monday 4th April 17:31

300bhp/ton

41,030 posts

197 months

Monday 4th April 2022
quotequote all
Just for completeness. If anyone else is interested in 7.50 x 16 tyres. It should be noted that there is a limited choice available these days. Sometimes remould (aggressive Mud Terrains) are offered in this size, but often they are based on a 235/85 and why too wide for a 'real' 7.50 x 16.

The XZL above is however a true 7.50 x 16 size.

Edited by 300bhp/ton on Monday 4th April 11:17

camel_landy

5,084 posts

190 months

Monday 4th April 2022
quotequote all
300bhp/ton said:
The XZL above is however a true 7.60 x 16 size.
???

Did you mean 7.50 x 16?

Either way, that photo looks to be 235/85, as it has the 4x lugs across the tread (I run XZL 7.50x16 on my 110).

M