Alright so this is the area I feel least knowledgeable. Can someone please explain to me everything about wheels and tires? I am looking at picking up some Rota Slipstreams and am either going 16X8 or 17X8. But what I really want to understand are all the terms floating around. I mean when Rally posts a calculator to help people figure out fitment, I dont even know how to fill it in or what it is telling me. So can I get some definitions? offset, backspacing, when a tire is listed 205/50-17 what does that mean. How does everything affect everything else? Thanks for any help or links.
Bryan

 

Wheel tech

Tire Tech

Alex

 

Thanks Alex!

 

Tirerack has a lot of info on the technical information section- read them all.

Then if you have questions try doing a search for treads in the past.

Many of the same questions are asked regularly.

So you are interested in Rota slipstreams?

What are you going to use the wheels for?
What tires do you think you'd be using and for what purpose?
Is your suspension lowered?
What is your budget?

 

I will be using the wheels mostly for street use, twisties, and the occasional track day. I dont know what tires yet but for the same purpose. I will be installing H&R sport springs which lower the ride about 1.25" and I am hoping for around 1500 for the set.

 

I felt like this, too, in the beginning. So here's my version of a chewable list of what you likely need to know (I'll explain these in everyman terms, 'cause that's what I am):

Winter/summer/all-season: Tirerack says it, and I believe it - tires are like shoes, so wear the right shoes for the right occasion. I use summers in summer, spring, fall, and winters in the winter. All-seasons are OK at everything, great at nothing, except maybe durability.

Tire width - This is the first # on the tire (205, 215, whatever). This is the width of the tire, and it's important because if you change the offset (which the slipstreams do) you can't put too wide a tire on the car without rubbing.

Aspect ratio (we'll call it tire height) - This is the second # (45, 50, whatever). This # has something to do with a ratio of how wide the tire is, but I really don't know what the hell that means, so to me, the # denotes how tall the tire is. Tall tires are comfy, short tires are harsh. Tall tires make highway driving more comfy because they put you at lower revs, and short tires help acceleration because they shorten gearing.

Tire/rim diameter - This is the last #. Lots of debate about which diameter to get for the MINI. General consensus is that smaller diameter = less unsprung weight = marginally better performance. I'm part of that sect and run 15 inchers on the track and 16 inchers on the street.

Offset - I really don't know how to define this at all, but I do know that as the offset goes UP (around 50), the wheels get closer to the brakes and in from the fenders. As the offset goes DOWN, the wheel is pushed out towards the fender. The sweet spot for offset on the MINI seems to be 35-45, although some will say 35 is too aggressive. The slipstreams come in 40, I believe.

Tire size calculator - This thing is freaking awesome. Type in your stock sizes as listed above and as shown on your tires. Then type in the sizes of what you'd like to put on the car. Hit calculate then see if it works! What to look for: speedometer difference (over 3% isn't recommended for daily driving, although many do it).
http://www.1010tires.com/tiresizecalculator.asp

You should be OK with a 215 or 205/50/17 on a sligtly lowered R56, but I don't actually know that.

Now the experts will and should chime in to make sure the above information is accurate.

mb

 

thanks mb. starting out is a little bit daunting.

 

OK, you want some handling and need to have them work with lowering springs.

205/50-17 is not a recommended size due to the taller than stock overall tire diameter. It is possible it could fit a MINI with stock suspension but depending on the width of the rim and the offset you'd risk rubbing.

Think backwards in order to select a rim or at least narrow down your choices. Most people choose a wheel then find a tire to fit. Since there are many good tires out there you can select a really worthy tire for your needs.

If we look at 16" tires the best size would be 205/50-16 which is about stock sized and should work with 16x8 rims. Check in the Ultra High Performance summer tire class at tirerack.

If you consider 17" tires then there is not as much to choose from-
205/45-17 stock sized limited choices
215/40-17 smaller than stock- should work but not as comfortable for street use due to lower stiffer sidewall 40 series tire.
215/45-17 is slightly taller than stock at 24.7" and might have limited clearance. Wheel offset becomes more critical with a lowered MINI. Offsets of about +45 to +48mm are best. +42mm would be at the limit of rubbing.

Are you going to use the tires at all for snow? If so then All Season tires would be worth a look.

How long do you want the tires to last? 1 or 2 years or longer than 2 years?
How many miles do you drive per year with your MINI?

 

for the visual learner



Wheel centerline = Wheel width / 2

Backspace = Wheel Centerline + Offset This is how much open area you have on the inside of the wheel (where the brakes are)

 

In terms of the calculators i post.....this is how i use them to gain helpful information.

If I'm looking at a wheel that is 16x7.5 offset40....i would the width of the wheel (7.5) and the offset (40) into the calculator. The way it works though is comparing it to another wheel.

The best thing to do, is compare it to the current wheels you are running. If you first plug in your current wheel numbers and then the new rota numbers.....it will tell you the difference. If it says that the new wheels will move 10mm outwards (away from the car)....you should measure your current wheels and make sure you have 10mm's to go without possibly rubbing on the arches.

The goal of the calculators is to provide an estimate of what changes will be made with your new measurements. Let me know if any of this needs better explaining

 

A little more to it then that. It's the cross section width of the tire at a specified point on a specified wheel at a specified pressure.

Aspect Ratio is a formula. That second number is a percentage. On a 205/50 the aspect ratio tells us that the height of the tire is 50% of 205mm or 102.5mm . A 215/45 would have a sidewall height of 45% of 215mm or 96.75mm.

 

You have a 2007 MCS with LSD. Lowering springs will reduce workable wheel offset to about +42mm to +48mm. Wider rims give less clearance but will fit wider tires. Lets assume no snow in your area.

Tires that do well on the street have good handling dry or wet but good comfort and low road noise, some have moderate tread wear and moderate prices about $100 per tire.

Rota rims are about $600 per set shipped or better. Advantage of smaller rims is lower weight and sometimes better selection of tires with more choices of side wall height. 16" rims allow for 40,45,50 and 55 series sidewalls. The lower numbers mean stiff responsive sidewalls better suited for performance driving but harsher riding for daily street use and usually more expensive. 17" rims restrict sidewalls to 40 and 45 series due to the height of the tires that will work and still fit the MINI. Rarely you can fit a 35 or 50 series tire either due to clearance issues or limited tire selection.

For street use 50 and 55 series tires are the most comfortable and also tend to wear longer but they are not as good for cornering as 40 and 45 series tires. Handling can vary alot based on tire design and tread pattern.

For the Rota Slipstream
16x8 comes in 4x100 bolt pattern with +34mm offset and 56mm hubbore or with +48mm offset and 56mm hubbore. It's easier to find the +48mm offset rim in different colors but clearance will be better with +34mm offset.

Another option is the Slipstream in 16x7 4x100 bolt pattern +45mm offset and 56mm hubbore. Advantage is slightly lighter weight rim, better fitment which is closer to stock rim size and offset, still fits the tires fine and look will be OK, better selection of finishes and a little lower price likely.

17x8 4x100 bolt pattern comes in +46mm offset and 56mm hubbore. Cost is about $100 more than the 16x8. Not sure of the stock on this size, I didn't find that much right now- check your sources. The large and wider rim will weigh more than the 16" by about 2-3 lbs each.

On tires-
Wheels and tires work best when matched for their sizes.

Lets look at a good and popular Max Performance Summer tire for the MINI
The Goodyear eagle F1 GS-D3 (280 treadwear)
In 205/50-16 $119 each fits rims 5.5-7.5" wide, perfect fit for 6.5" rim, 22 lbs, 24.1" tire diameter. Note that it can stretch on a 16x8" wide rim but it is not as good a fit. A 16x7" rim would be better.
If you really like the 16x8 rim then a different and wider tire size might be better. Using the same tire we find it in 215/40-16 $136 each fits rims 7-8.5" wide, perfect fit for 7.5" rim, 19 lbs, 22.8" tire diameter. This match of rim and tire is better but it does cost more and the tire diameter is much smaller than stock by 1.5" which means speedometer and odometer error will be present. Also 40 series tires are not as comfortable for daily street use.

Same tire in 17" sizes (205/45-17 not available)
205/40-17 $128 each fits rims 7-8" wide, perfect fit for 7.5" rim, 22 lbs, 23.4" tire diameter. 84 load rating
205/50-17 $158 each fits rims 5.5-7.5" wide, perfect fit for 6.5" rim, 22 lbs, 25.1" tire diameter. 93 load rating
215/40-17 $153 each fits rims 7-8.5" wide, perfect fit for 7.5" rim, 19 lbs, 23.8" tire diameter. 83 load rating
215/45-17 $132 each fits rims 7-8" wide, perfect fit for 7" rim, 22 lbs, 24.6" tire diameter. 91 load rating
225/45-17 $177 each fits rims 7-8.5" wide, perfect fit for 7.5" rim, 24 lbs, 24.9" tire diameter. 94 load rating

Notice prices and tire diameters. Stock tire diameter is 24.3" and taller tires have much less clearance when your suspension is lowered.

So if I had to suggest a wheel and tire-
16x7 rims +45mm offset 4x100 bolt pattern
Goodyear Eagle F1 GS-D3 in 205/50-16
Good for street use but still good handling for occassional performance driving.

And for those on a restrictive budget you can use stock R102 16" S-winder OEM rims 16x6.5" and mount the Goodyear Eagle F1 GS-D3s on them and get good performance that way. S-Winders are a light 16.6 lbs each while slipstreams in 16x7 might be about 14.5 each.

 

thank you Minihune. That is, wow, perfect. Thank you for the wisdom. I think of all the sections of NAM this is the clearest presence of a Mod I have seen, which I think is great. Thanks!
Bryan

 

OK, now give classes on your own with your new found knowledge.

Basically you want to keep near to the stock sizes and specs and tweak them a little for your interest.

If you look at wheel design for the MINI the wheel sizes are picked on purpose not random. Each rim has a perfect tire size and that size works for the MINI for a given task- usually street use. However we have other needs sometimes so we make adjustments and go wider on rims and wider on tires but run into rubbing issues because things don't fit as nicely.

You can get very wide rims to fit the MINI but you'd need to widen the fenders and cut the plastic or replace it with flaring to make room for the extra wide tires even as large as 275mm. But are you going to run those on the street? It would look funny if you do that to the fenders then ran 215mm street tires for daily use.

Have fun with your MINI. Feel free to PM me when needed.