Tyres and Rims

Submitted: Sunday, Apr 20, 2008 at 18:11
ThreadID: 56817 Views:2573 Replies:4 FollowUps:4
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My TDV8 trayback comes with 265/70R16 tyres on 7 inch rims.

The speedo over reads by 6%, ie, when it is showing 100kph I am actually doing 94kph.

If I fit 285/75R16 tyres this error is effectively cancelled out.

However, this size tyre requires an 8 inch rim, minimum.

In reality, what are the risks involved in putting this tyre on a 7 inch rim?

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Reply By: Member - Longtooth (SA) - Sunday, Apr 20, 2008 at 18:26

Sunday, Apr 20, 2008 at 18:26
Don't know, but in my shed there are four in this configuration that have perfect wear on them. Not my tyres but am considering this configuration for my next set of tyres as there does not appear to be any problem with them. I am told they were fitted to the rims by a well known tyre retailer and they considered there would be no problem.
AnswerID: 299467

Reply By: Member - Phil G (SA) - Sunday, Apr 20, 2008 at 18:30

Sunday, Apr 20, 2008 at 18:30
Gday Stephen,

According to most of the tyre specs, 285 needs a 7.5 inch rim.
So IMO the risks of fitting to a 7.0 inch rim are theoretical. The benefits are that you have a tyre that will be easy to reinflate as a tubeless tyre, and is less likely to roll off the rim.

I've noticed a lot of the new vehicles that have been thru the aftermarket stuff, have the 285's on the 7 inch rims and they look OK, so you'd be unlikely to get picked up on it. Only problem might be with the tyre fitters, if you find one who sticks to the letter of the law to the mm.

cheers
Phil
AnswerID: 299468

Follow Up By: Member - Phil G (SA) - Sunday, Apr 20, 2008 at 18:53

Sunday, Apr 20, 2008 at 18:53
Forgot to add,
#1 you may need to raise the tray to get the necessary clearance for 285s.
#2 You may want to consider 255/85R16. They are just a touch taller than 285/75R16. Maxxis have a AT tyre called MA-761 (LINK to Maxxis site) which has a 3-ply sidewall thats available in that size. Alternative brands are BFG Muddies and Coopers, but the latter are only 2 ply sidewall.
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Follow Up By: Member - John H (WA) - Monday, Apr 21, 2008 at 12:12

Monday, Apr 21, 2008 at 12:12
I went down the route of BFG muds in the 255/85R16 size on the standard alloy rims. As Phil mentioned they are a tiny bit taller than the 285/75R16's.

Personally I prefer a narrow, but tall tyre for less rolling resistance, and plenty of ground clearance.

Here's a pic below (I hope it comes out ok). BTW they fit fine with a 2" lifted suspension.

John



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Reply By: Member - Leigh (Vic) - Sunday, Apr 20, 2008 at 19:48

Sunday, Apr 20, 2008 at 19:48
For what it's worth I went down the path of 255*85*16 Coopers and turned a negative reading into a minor positive reading.
AnswerID: 299496

Follow Up By: Member - Leigh (Vic) - Sunday, Apr 20, 2008 at 19:49

Sunday, Apr 20, 2008 at 19:49
Should have mentioned this was on 7" rims
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Reply By: Gone Bush (WA) - Monday, Apr 21, 2008 at 15:18

Monday, Apr 21, 2008 at 15:18
Thanks to all respondents.

I'm particularly interested in the 255/85, I hadn't thought of them before.

John H are your M/Ts noisy on the road?

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Follow Up By: Member - John H (WA) - Tuesday, Apr 22, 2008 at 10:20

Tuesday, Apr 22, 2008 at 10:20
Yep, they are noisy compared to AT's - you can hear that 'mud tyre whine' as driving along the blacktop. Personally it doesn't bother me at all, but some people don't like it. As I usually have the stereo playing, that gets rid of any other sound anyway.

I'm sure a bit of searching will find other brands with 255/85's available (such as the cooper ST's mentioned). I didn't look too hard as having used BFG muds on previous vehicles, I was happy to stick with that.

Hope the info helps.

John
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