Hi all,

I've read and read, and had so many different opinions.. Has anyone done this in practice, and if so please tell me what is required.

I have a set of R888's in 225/50/15 that I want to get installed. I have heard that with the 225 tyres (on 6" rims -- widest I can go with r888) I will have guard issues. Now, I am prepared to roll the fenders, remove plastic guard inside the fenders etc .. Just need to know what I will need. The car isn't too low, max ride height with Toda DA coilovers, probably about 10-15mm lower than stock. I've read also that some people have had to use spacers? Hmm ..

I just want to do it once and do it right, rather than effing around with the car off the road!

If someone can tell me what is required I would be VERY appreciative.

 

225/50-15 is too large in diameter for an Integra and will rub, big-time. It will also reduce your acceleration. If you want to get 225 treadwidth tires, you can get 225/45-15 but those must be mounted on wheels at least 7" wide. For the stock 15x6 rims on your car, you'll need to get 205/50-15 tires.

 

Ok couple of questions:

1) I know it will rub, I understand there is a solution. I am asking what is required to make these tyres fit -- I will be removing the inner guard & rolling the fender. It is only 20mm extra clearance required, not a massive amount. Also I am not riding ridiculously low.

2) How do you figure these would hurt acceleration? I am not really increasing the unsprung mass a great deal and the increase in overall diameter is minimal. Now if I was going to 16" wheels or 17" wheels I could understand.. Also by retaining a 6" wheel I am reducing unsprung mass over a 7" wheel, and the 225 tire will fit a 6" rim according to Toyo.

3) So -- Who in the quest for additional contact surface has gone for the larger 225 tyres? I know a lot of civics run them, and some DC2 run them in the front only with 205 in the rear (makes sense, staggered).

My point is --- There is a way to make these fit, I know people have run them before with modification. I just can't find exactly what was required...

Thanks for your help though!

3)

 

Ignoring mass, the diameter of the 225/45-15 sized tire is 22.8", while the 225/50-15 is 23.7". That is a reasonable difference. Enough to noticeably affect acceleration.

Toyo lists the 225/50-15 as supporting a 6"-8" wheel width.

However, the 225/45-15 size that nsxtasy listed is only approved for wheels 7"-8.5" in width.

A wider tire does not provide a larger contact area. Only increasing the car's weight or lowering the tire's pressure, could accomplish that.

Most who do go for the wider tire (and a wider but shorter contact patch), run one that isn't larger in diameter. Increasing both width and diameter, is often difficult to avoid rubbing with.

If you really want to make them fit, then you'll need to get them mounted on your wheels (I don't see an offset listed anywhere here for us to guess where they might not fit), and go test fit to find where you'll be lacking clearance, and then correct that issue.

Lower offset wheels, probably need to pull and roll fenders, if not outright flare them. Higher offset wheels, you might rub the shock tower or spring.

On a side note, you in the UK? (the y in tire is why I'm asking)

 

Thanks for the reply.

I was relating back to a 205/50/15 profile -- Not a massive differential but yes it is slightly larger diameter, but only around 1cm I think (from memory, haven't done calcs here).

I would've thought that a wider tyre by definition will have a wider contact patch -- Take it to extremes. a 330/15 and a 135/15 --- Which has the greater contact patch? I understand that in general that just increases the surface area (which doesn't necessarily increase grip, as it is co-dependant with weight acting upon the surface area) but I would also think that with a 225 vs 205 that the grip threshold is actually higher for a given load .. ?? I.e. if I am over-loading my outside front on turn in, providing a slightly wider tyre may increase the threshold available ?

I am from Australia -- No whinging here! haha

Wheels are standard DC2R 15" -- I think +38 Offset and 6" Wide.

And besides all the above -- I've got the tires, I just want to make them fit, almost a test to see what the grip level is like. I will then try a 205 on the back with 225 up front..

So -- We know the tyres fit on the rims. We know that some modification is required. I don't have a second set of wheels at the moment, so I kinda want to get it right (or close to) first time.. Thus booking into body shop for work then into tyre shop.. (or Tire )

I noticed some marks on the inner-guard from rubbing (some time in the past) so maybe with the fenders roller / flared, the spacers some people use are to decrease the offset (is that right? or increase .. argh!)

Thanks again.

Again thanks for help -- continued input is appreciated.

 

Toyo lists the R888 205/50-15 as a 23" diameter. The 225/50-15 is 0.7", or 1.8cm, larger in diameter.

Yes, a wider, but shorter, contact patch. Total size will stay the same, only the shape changes.

On the same car, and ran with the same pressure, they will both have the same sized (total area) contact patch.

It could. This is one of those contested items. The tire deformation is different with different widths, as is the slip angle max cornering traction is achieved at. The best recommendation in general to get more cornering traction, is use better tires instead of wider tires.

The biggest advantage of a wider tire is having more total rubber to spread the heat over. This also means more total rubber to wear down (longer lifespan), and each part of the tire is in contact with the road for less time (shorter contact patch) which generates less heat as well. This can certainly be beneficial on track.

I had to look up "whinging". I might need to add that one to the "English to American" dictionary I have...

Rub marks on the inner plastic fender liner? I've got those as well on my DC2 (mine are from running excessive camber settings without low offset wheels).

Lower offset wheels will help with that clearance, and spacers can be used to effectively lower the offset. Don't forget to install extended studs if you go past (I think) 5mm on the spacer, and try to use ones with the hub-centric lips on both sides.

You're just going to have to test fit and adjust from there on this one.

 

Tunern00b is providing you excellent advice on all counts. Regarding the contact patch, with normal tire pressures to support the weight of the car, the size of the contact patch stays the same. For example, if you inflate all the tires on a 2640-pound Integra to 33 pounds per square inch, the total area of the contact patches will equal 80 square inches. And that result is true regardless of whether you're using 185-treadwidth skinnies or 225-treadwidth steamrollers. You can read this article (from one of your publications Down Under) for more information.

Frankly, I think you made a mistake buying the wrong size tires. Your best bet is to sell those tires and buy tires that fit - either 205/50-15 if you want to use your 15x6 wheels, or get some 15x7 (or wider) wheels and 225/45-15 tires.

On the racetrack, I'm using 205/50-15 R compound track tires (the Toyo RA-1 and Nitto NT-01, rather than the Toyo R888) on stock 15x6 rims on my Integra Type R and they work just fine.

 

.. ok, so why don't you run 185 treadwidth then? Why running 205? Plenty of civic race cars and integras run 225/50 I've seen them. I just thought someone may have been experienced in the modification to make them fit. It can be done, I just want to know how. Not that I bought the wrong tyres etc -- I bought them knowing I needed to modify the wheelarches to make them fit ..

I've been using 205/50 since the beginning, I am trying something new / different.

Thanks for your help all the same..

 

And yeah I see your point regarding contact patch.. Makes the traction threshold theory sound good though.

 

He's not saying you have the wrong tire size because of width, but because of your wheels and tire profile.

Your tires are too tall and will hurt acceleration (that difference will be noticeable). Also if you do drop down to the proper width and aspect, the tires require you to have a wider wheel (15x7 or wider).

A lot of civics use 225/45/15, i've never seen a civic or integra use 225/50/15 unless they want that extra height to give them better gearing to offset huge power usually brought on by some type of FI. Also the reason I'm guessing he's using 205's is because a 185 would probably over heat and drop out of it's optimum temperature range.

 

Oh, yeah sorry. Its about to be supercharged, shooting for around 300hp.. So your on the money. Took it to a body shop and got it all done, got the fenders rolled out and used 5mm spacers to clear inner.. Actually sharper turn in I think from increased track.

 

Hi - To give some feedback to the thread. I've fitted the 225/50 tyres and I don't know how, but at max height on the Toda DA's, they clear everything *just* .. Took it for a drive and no rubbing .. This is with the inner plastic guard removed.

But so I can lower it, I will get the fenders done in anycase - Just wanted to let you know.

 

oh and with respect to the comments regarding the wider tyre not increasing contact patch.. This was my point. I agree with what you are saying for a static car -- One not in motion, or taken at an exact moment in time.

But when a car is cornering, there is an effective weight transfer onto the outside front tyre which when it overcomes the grip threhold of the tyre with lose traction and understeer. during this weight transfer the tyre contact patch would have increased to a point where it could provide no more mechanical grip.

Another thing (or just another way to look at it) is that for a given cornering G the wider tyre has a lower slip angle. ie less distortion. The tyre starts to slide when the slip angle reaches a threshold so a wider tyre can naturally generate more grip.




Now, with a 225 tyre (or a 'wider' tyre) as there is more potential grip available (20mm more rubber) when the weight transfer occurs this tyre will be able to provide a higher overall grip threshod thus increasing the load the tyre is able to handle.

Or am I wrong? Looking at it from your perspective, at the same given load ('x')

 

When cornering, the contact patch on the outside tires becomes larger; the one on the inside tires becomes smaller. The sizes of the contact patch also vary depending on what the suspension is doing; when the suspension compresses (such as at the bottom of a hill), the patches may all enlarge, just as they will shrink when cresting a hill.

The bottom line, though, when shopping for tires, is that you'll get the best performance by looking for the stickiest tires, rather than the widest tires. And larger diameter tires (such as 225/50-15 rather than 225/45-15) generally result only in problems (slower acceleration, rubbing) without any performance benefit.

Since you already have bought those oversized track tires, why not just try them out? I'm pretty sure they're going to rub, especially with the suspension travel you typically experience on a racetrack, so you might want to bring another set of tires along to the track with you in case the oversized tires turn out to be unusable.

 

Well, I'm getting the work done to the fenders in any case, so I can get a little lower.. And then off the to track later this month. thanks for input,.