What size tires for 16" alloys ?

[A1ex]

No worries.

Makes a big jump on your final drive too; Changes your 4.26 to 4.55 which is almost a race final drive Be good for a track day

[NafemanNathan]

Do you happen to have the figures for 17"?

If it's right in my head changing from say 215/45/17 to say 205/45/16 is a massive difference

Overall diameter of a 5th gen stock wheel (205/50r16) = 611.4mm

205/45r16 = 590.9 (-20.5mm undersize)
215/45r16 = 599.9 (-11.5mm undersize)
215/50r16 = 621.4 (10mm oversize)
225/45r16 = 608.9 (-2.5mm undersize)
225/50r16 = 631.4 (20mm oversize)

205/40r17 = 595.8 (-15.6mm undersize)
205/45r17 = 616.3 (4.9mm oversize)
215/40r17 = 603.8 (-7.6mm undersize)
215/45r17 = 625.3 (13.9mm oversize)
225/35r17 = 589.3 (-22.1mm undersize)
225/40r17 = 611.8 (0.4mm oversize)

[mercutio]

Is it really that noticeable in every day driving?

Only asking cos I have some 16s but no tyres atm if it's worth it might change from 17s...

hell yeah its noticable lol

[RattyMcClelland]

Again overall circumference is overated. You guys are worrying about it too much.
The Preludes caster and camber is designed to run with a 205/50 sidewall so ideally you want to stick to a 4" sidewall.
So on 16" id only go with either 205/50 or 225/45.

Here is a good article explaining what im on about from Prelude power by Jhall.

Forget tyre sizes as this refers to 17" but 16" still apply.






225/45R17 is about 3 percent taller than stock in overall diameter however the tire height is almost spot on to the sidewall height of the stock size. 225/45R17 will change the gearing due this difference in overall diameter but as far as handling goes 225/45R17 will generally give you a better contact patch than 215/40R17. The reason for this is even though 215/40R17 is similar to the stock overall diameter (it's actually off by about 1 percent) it has a lesser than stock sidewall height by a little more than half an inch. This difference in actual tire height is a problem for two main reasons, the first being that this shorter tire is not able to absorb energy from imperfections in the road, such as large cracks and bumps, because it does not have as much sidewall. The second reason has to do with camber curves, as the suspension travels throughout it's range of motion the camber, or angle of the suspension to the ground, changes. The reason for this change is because as the car begins to lean in a corner the angle the wheel is at needs to be changed because otherwise only a small portion of the tire would actually be on the ground. This is an example of what would happen if the two arms were the same length.



Notice how in the upper picture even though the wheels are at different levels they are still flat on the ground. Now in the second picture it shows the "car" leaned over with the same equal length control arms. Notice how the tire on the left is only touching the ground on the outside and the right has the inside touching without much, if any weight, on the outside part. When manufacture design a car they want to avoid the situation in picture two so they design the upper arm and lower arms to angle the wheels as the suspension moves. When the arms have different lengths they create a certain curve called a camber curve.



This sample camber curve shows the relation of wheel camber to suspension travel. At any given point a car with non-parallel double wishbone suspension will fall somewhere on the graph. Point A on the graph demonstrates where the wheels are when the car is not on the ground which can happen in situations like the car being on a jack or lift. The line marked static shows what kind of camber the wheels will have when the car is at rest. Area B shows how much cambers the wheels have when the cars suspension is at it's highest travel.

So now how does this camber chart relates to tires, wheels, and lowering springs. First thing I'll tackle are lowering springs.

Lowering Springs: Most lowering springs run a firmer spring rate and drop the car a certain amount. When a car is lowered and alignment remains unchanged the graph above would still look exactly the same but the one difference is that the static point, where the car's suspension is at rest, is changed.



If the car was lowered 1.25 inches the new static point would be where point C is. Notice how there is a little bit more negative camber than the previous static point. If the car was aligned, or a camber kit installed, the curve would be shifted over to the right but only shifted, the shape of the curve would remain exactly the same. The reason for this is because unless the length of a control arm is changed this curve will always be exactly the same. In fact camber kits can actually prevent your car from getting sufficient negative camber in a hard cornering situation especially with stiffer springs that restrict suspension travel. Now for the wheels are tires portion.

Wheels and tires: I'll start off by saying that when it comes to camber, overall diameter makes no difference. If someone were to some how fit 22's on a lude the camber would be the same as if the car had 13's. Since camber curve has to do with the relationship of the two control arms the wheel/tires overall diameter makes no difference because the wheel is not part of the suspension, it just attaches to it. Now for the tires, the stock tire setup on the 5th gen prelude was a Bridgestone RE92 205/50R16. The car was designed around both this size and this tire. This tire has a sidewall height of 4.0 inches which is decently tall, it's not a low profile tire but it also isn't a giant suv tire.
So what does sidewall height have to do with proper camber, didn't you say the overall diameter didn't affect the camber curve? Neither the tire size or wheel size affect the camber curve but just like suspension, tires have their own tricks.

Camber curves aren't perfect, they can't be because it isn't possible to make a car that rides well, wears tires well, and still retains perfect camber in corners. So manufactures usually stick with a combination that is a middle ground for both and, depending on the car, one will be more favored than the other. A good example is the original Volkswagon beetle, the tires are almost perfectly flat when it's sitting, but if you've ever seen one take a hard corner, the inside part of the tire is hardly on the ground and the outside is being very heavily weighted. Back when that car was designed camber curves really weren't too much of a subject to worry about. Now for how tire sizes affect contact patches.

The contact patch is the overall footprint of the tire with weight distribution factored in. If you stand on your shoe it is make a contact patch. If you are keeping your foot flat, step in water, and then step on dry concrete you will notice that there is more water around the heel area and ball of the foot. This happens because the weight distributed on the both the heel and ball of the foot is far higher than the rest of the shoe. Tires have a similar thing happen except since they are round and filled with air they put down a perfect contact patch at 0 degrees camber. Now when you lean a car over the suspension begins to create negative camber but since the car is leaning the tire is still flat right? In a perfect world this would be true but since camber curves aren't perfect the contact patch usually isn't perfect, some parts of the tire will be experience more weight than others. No matter what size tire you put on, this imperfect amount of camber will always be there BUT there is one thing that can compensate for this imperfection, sidewall. Since a tire is not a flat piece of metal, it has some give and flex and that being true the tire itself acts as a bandaid for the imperfection in the camber curve. If you were to put a 1 inch sidewall tire on a car that was designed to have a 205/50R16 with a 4 inch sidewall it would give a horrible ride and wouldn't handle worth a crap because that 1 inch tall tire wouldn't be able to compensate for the imperfections in both the road and the camber curve. Take that same car and put a 225/45R17 with 4 inches of sidewall and the camber curve would be very close to as effective as it was with the 205/50R16 even though the overall diameter is taller than the 205/50R16. Put a 215/40R17 on that car and you will experience better steering response, but once you got the car leaned over it is very possible that the contact patch would be further away from ideal than either the stock size, or the 225/45R17. The reason is because the 215/40R17 has 3.4 inch sidewall so it cannot handle imperfections in the camber curve as well as a stock size because the curve itself was designed to be the most effective on the stock size.

To sum it up overall diameter means nothing outside of gearing, tire size and sidewall height are the important factors. Match the sidewall height of the stock tire size the car was designed around and you will most likely get the best results. When it comes to tire sizes it all depends on the look you're going for and what kind of performance goal you have. Smaller sidewall tires look nicer on bigger wheels and can have little affect on gearing but handle like dog crap compared to stock. Bigger wheels with tires that match stock sidewall heights can be better for handling because one can maintain effective camber and actually run a wider tires. But at the same time, gearing ratios are thrown off, there is more unsprung weight, and acceleration is slower. It all comes down to what you want to do with your car.

[NafemanNathan]

^ Most of that is irrelevant and just outright confusing Plus you cut and paste also contradicts your opening paragraph

I agree that you can sway from stock size if you want to achieve something different (eg. smaller tyres for better accelleration, wider tyres for better contact), but you need to know what you are doing and what you said so far is bad advise.

You cannot tell people that 4" side wall is best. What the hell does that mean?... I can 13" rims with tyres with a 4" side wall?! Or I can run 18's with 4" side walls?!

Think of it this way, the tyre and rim make a one-piece cylindrical object... We'll call this the wheel. If you want to maintain the correct speedo reading (fairly important to most) standard acceleration, top speed and gearing, run a wheel with stock offset and stock width and not have any rubbing issues, what else matters?... Not tyre height because as I've already pointed out, if you run 13's or 18's with tyres with a 4" side wall you're pretty much screwed, but you can run a 13" or 18" rim with stock offset and tyre width if you run the correct ratio to create the same as stock overall diameter.

Yes, your ride comfort would be sacrificed if you did decide to run 13's or 18"'s, but you wouldn't run into any rubbing issues, you're speedo would read correctly (give or take a mile due to the closest available match) and your accelleration, topspeed and gearing would remain as it should as well.

I really can't see how you're thinking what I've said is wrong and that overl diameter isn't important

[RattyMcClelland]

Overall diameter really isnt important. You wont notice a difference unless its extemely different. The difference is really only 10mph maybe ontop of the top speed if comparing a 205/40 to a 225/45.
But yes weather is a 13" or an 18" id still stick to a 4" sidewall unless serious rubbing that KY cant cure happens. This is an important factor in double wishbone suspension. That article was copied from an autocrosser in the US.

[NafemanNathan]

Ok, well all the info's there for everyone to make their own mind up now anyway