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Discussion Starter #1
Folks - seems like tire buying season. Have couple of questions before I dive in and buy anything.

Thinking of going with a set of Stormer's from ebay - which I've already bid on.

1. The offset on the Stomers listed are 50mm with a 9.5" rim diameter. So based on a site provided by umbertob on another topic (http://www.1010tires.com/WheelOffsetCalculator.asp) I am less 4mm (closer to the Arm) based on the stock 19's with 9"

Will the above stormer wheel work with a 285/50 or so I need to get a 275/40

With a 285/50 I will get a diameter of 31.2 (31.29 based on Cooper site )
With a 275/45 I will get a diameter of 29.7 (29.82 based on Cooper site)

I've read that Drevs runs on 285/50 with no issues or spacers (initially he stated on 1 topic that he had spaced and then removed it and survived the test run without the spacers).

So based on the offset and the diameter can I buy the 285/50 or am I stuck with 275/45.
 

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FTR.

A 20 inch diameter 'Stormer' which you refer to as 9.5" wide allows the fitment of wider rubber compared to the OEM 9" wheels !

Yes the wheels will sit 4mm closer to the body work of your RRS, but since the wheels are an extra 0.5" wider than standard, this allows the relevant tyre to sit more vertical rather than bulge at the sidewalls and consequently there is no tyre rubbing.
By going to a 285mm broader section of tyre will not be an issue for the overall running clearance around the front fenderwells, since the wider wheels allow a flatter footprint and slightly reduced diameter of 30.72" in rolling diameter which is cool as Bro' ?

Cheerio,


Vinniman
'88 Highline
Perth, W.A.
 

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Discussion Starter #3
Thank you Vinniman, could you tell me how you arrived at this number of 30.72. This site (http://www.miata.net/garage/tirecalc.html) does not account for what you mentioned below regading wider rim I guess. Based on my readngs on this site, am I correct that the max we could go up to is 31.5. So based on you calculations (if I can have your forumla) can I do a 275/55?
 

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FTR.

Thanks to 'Goosey Loosey's' illustration, too bad I'm overseas for 2 months so I'll miss out on Australia Day action in Perth, W.A.
All tyre manufacturer's state overall diameters for a specific size of their products on a set rim dimension at 3/4 max. inflation !
By calculating the metric proportions, most suppliers state a degree of +/- or measurements within 3% tolerance of their sizing, depending what deviation exists with the style of their tyres & relevant wheel widths greater or lesser than the recommended ?
Normally this is a factor of 0.5" for rims wider or shallower than necessary and you may find blokes quoting 32"s as a RRS max.
So a 275/55R20 tyre will measure out 30.91" in overall running height on a 20"x9.5" wide 'Stormer' wheel as it is the widest rim.

Cheerio,


Vinniman
'88 Highline
Perth, W.A.
 

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Discussion Starter #6
Thanks. Coooper states
31.93 for a 275/55 on a 8.5" rim
31.29 for a 285/50 on a 9.0" rim

So Vinniman - are you saying since I'm going with a 9.5" rim I should be fine and clearence should be ok on any of these. Do I get concurrence from all guru's out there.

So next question is - will a 275/55 be better than a 285/50 with more side wall. Of course handling will be slightly less I assume.
 

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One thing to keep in mind is I believe Drevs was using OEM 20"s. IIRC he rubbed at full lock when the tires were new and decided to go with the spacers because it was going to rub on the upper control arm. The 275/55 is going to be wider, higher up (if that makes sense); will the 10mm less section width (only 5mm per side) counter act that enough, I can't say. I think it was even Drevs who tried that size and decided it wasn't going to work.
 

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Discussion Starter #8
TripleE-If Drevs ran on OEM's I belive those were 9" rim widths with 285/50. The rims I intend getting are 9.5 ". So hopefully it should work right?
 

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Is the 20x9.5 wheel 4mm closer than compared to an OEM 20x9? I see above you have it compared to the 19x9 and I don't know if the offsets are the same for OEM 19" vs. OEM 20". If the wheel is 4mm closer compared to the OEM 20x9 then the 285/50 it's likely not going to work without a spacer as per Drevs:

Drevs said:
I am using 5mm spacers on the front. Otherwise the upper control arm is about 1mm away from the inner sidewall of the tire... not good. Also, this minimizes a very slight rub on the plastic wheel well, right behind the intercooler exchanger.
Found here: viewtopic.php?f=5&t=18663&p=131444&hilit=upper+control+arm#p131444

5mm from the tire to the arm is probably the minimum you'll want to be away as you need to factor tire roll when cornering.
 

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AFAIK, the 20" OEM rims on the Sport are all 9.5" wide, including Stormer and standard S/C designs. I wouldn't chance those 275/55s myself. I think they'd rub too much on the inner wheel wells and possibly on the fenders when steering. However, I don't think we have anyone here who tried that size before, so they may turn out to be OK.
 

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Discussion Starter #11
That would be approx $1000 experiment to go with 275/55. Let me see if the shop would let me try the 2 front wheels with that size. Doubt it, but worth a shot.

Thank you all for the help !!!
 

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FTR.

I can recall the RRS S/C models down-under were fitted with optional 20"x9.5" alloy rims sporting 275/45R20 Continental tyres !
Which meant the static rolling diameter measured out to 29.24" in overall height, bearing in mind those wheels are 3mm closer.
So if "Drev's" went & bolted the same tyres in the same size as your future 'Stormers', his rubber clearance would be 3mm less to the fenderwell of his truck since the rims on your wish list are +50P Positive offset where as his are most likely +53P offset ?
Remember conditions you will be experiencing off-road to answer your question if 275/55R20 is better than 285/50R20 tyres all relates to the terrain. If you are likely to traverse mud, than the narrower tyre is preferred so mud evacuates from the fenders.

Cheerio,


Vinniman
'88 Highline
Perth, W.A.
 

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Thanks for the clarification b, from the original post, I thought it was a 9".

Not sure what he tried, but here's the quote:
Drevs said:
lakbum said:
I've looked through the forum to see if the Pirelli Scorpion ATR's in 275/55/20 would fit on the wheels of the RRS S/C. Do they?
Yes. Just don't mount them on your RRS. :)
I think I tried that size (before settling on the 285/50-20) and it wasn't even close.
 

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FTR.

Here are some other aftermarket Centerline wheel options in 20"x8.5" wide running +32P Positive offset suitable for the RRS's !

Just be mindful of other parts of the suspension system when Plus sizing rims onto your ride, as I'm sure RRS S/C models came standard with 'Dynamic Response' versus the HSE versions, so improvements to the dampers would normally be upgraded too ?

Cheerio,


Vinniman
'88 Highline
Perth, W.A.[attachment=2:2k3eos29]crosfire.jpg[/attachment:2k3eos29][attachment=1:2k3eos29]escape20.jpg[/attachment:2k3eos29][attachment=0:2k3eos29]tomcat20.jpg[/attachment:2k3eos29]
 

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Discussion Starter #15
Done deal folks - Thank you all for your help.

Ordered the Stormers - should be here Wednesday. Shopped around and Discount Tire has them 285/50 for $186 each.

On to my next project, replacing oem muffler; ordered the magnaflow muffler and tips - anything in between gets replaced with pipes ...

Thanks again to everyone for the help on the wheels.
 

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FTR.

Congrats & look forward to the pic's with your combo on-board ? I'm heading up to Guadalcanal for 2 months so happy trucking !

Cheerio,


Vinniman
'88 Highline
Perth, W.A.
 

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2006-2009 Range Rover Sport
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vinniman said:
By going to a 285mm broader section of tyre will not be an issue for the overall running clearance around the front fenderwells, since the wider wheels allow a flatter footprint and slightly reduced diameter of 30.72" in rolling diameter which is cool as Bro' ?
Good luck on your trip Vinni.

Maybe on the flight over you can check my calculations on something because I don't understand how moving the rim width 0.5 in one way or the other makes such a drastic change in tire diameter. Based on the 9 in rim the 285 tire per the previous posts is 31.2 in dia. You say moving this tire to a 9.5 in rim reduces the diameter by almost 0.5"?

Since you're a civil engineer, just for fun, calculate the difference in sidewall angle assuming the sidewall on the tire mounted on the 9" rim is vertical. Then recalculate the apparent sidewall height by moving the bead out 0.25" on either side. I assumed a 3" sidewall height (the angle changes about 5 degrees), and I can't get close to a 0.5 in change in overall diameter. What don't I understand?
 

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GooseyLoosey.

The two points I've made reference to are 'overall diameter' and "static rolling diameter" which I'm sure you can understand ! !

All tyre manufacturers state a section width dimension on a recommended rim width for their specific product with respect to differences in tread depth and the like, so the resultant shape of the tyre is effected by wheel width at the same inflation level.

Here's an example, go to the www.generaltire.com web-site and view the Grabber UHP product line and take note of 20" listings.
The 275/40R20 and 275/45R20 sizes have a different section width of 10.9" versus 10.7" respectively, yet are 275mm across ?
Apart from the different aspect ratio the recommended rim width that they used to measure was 9.5"s and 9.0"s respectively.

Go with your kid & measure the top of your back tyre to the ground and check what the measurement says versus the tyre size.
The rest of the forum members appear to understand with comments and observations made with their personal experiences.

Cheerio,


Vinniman
'88 Highline
Perth, W.A.
 

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Vinni,
Yes, I’ll admit I don’t understand many of your posts. I think its the non sequiturs. For example I was asking about the diameter (overall, static, or psychotic) and you are now talking about section width being wider on the 9.5 in rim than the 9.0 rim which is true and actually goes counter to your statement that the 9.5 in rim would fit better with no tire rubbing.

Certain tire sizes always run clear, then there are the tire sizes Frisco posted, which may or may not w/o some rubbing. When someone posts a question about whether a specific tire fits (especially a size that’s potentially gonna have some rubbing), they generally want to know if anyone who has the vehicle has tried it and what the result was. Going to a table, guessing, or consulting a magic 8-ball, getting a positive answer, and posting that they will work is not good practice.
 

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Cool Gooseyloosey.

There are other owners on this forum placing illegal size tyres that "fit" onto certain size rims but may not be relevant to their situation, i.e. towing or carrying a load which are outside tyre manufacturers recommendations yet suit them down to the tee ?

If any of us wish to void our vehicle insurance policy then those can go straight ahead, but specifications are made for a reason.
Tye resellers have been known to deny sale or fitment of a said tyre to a size rim or vehicle because of public liability issues.

When you've worked in a tyre shop for years, done plus sizes on several vehicles, including shocks, springs(domestic or import) and own a vehicle under this forum with or without air suspension the dynamics of the tyre/wheel game need to be qualified !

Yes even I have difficulty understanding your references on this post, but it doesn't stop Gooseyloosey providing any feedback. So like I said, go and measure the tyre height on your ride with the size stated on the sidewall and we can discuss the answer.

Cheerio,


Vinniman
'88 Highline
Perth, W.A.
 
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