Hi!

Thinking of changing from standard 15 inch wheels to 16s with 215/45s here in the UK. Any ideas on whether this is good or bad?

Cheers.

 

its not bad...your steering radius will become wider,...thas the only negative I can think of

 

What do you mean by steering radius?

 

I think it also means turning radius

 

i've had no problems... it's standard sizing for the jdm 98specr.

steering radius?!?

 

I have 225/45/16s and have had no problems (apart from a little rubbing at full lock). I am not sure how much PZeros cost on that side of the pond, but I would strongly recommend them in this size.

 

Cheers guys, I think I'm ready to spend some money now!

 

George, you look at that Speedo ... too much!

 

The speedo inaccuracy is 2% - both speed and distance and underreported because of the larger diameter tyre.

However, the stock speedo is notoriously innacurate (and overreports by several percent by all accounts) so 2% is not significant.

Steering effort is increased (which I like) and the wide and sticky PZeros do make the car follow ruts in the road a little more, but the increase in cornering grip over stock is quite significant.

 

For our torqueless stock ITR, increasing the overall diameter of the wheel would cost you acceleration. You would feel it significantly when going uphill.

True that this size is the OEM size for the 98spec, but 98spec has different gear/FD ratio and compression, and max torque appears earlier (I think it's 2K rpm but not sure).

But if your car is modded then the difference might not be too noticeable.

 

My car was not modified when I switched wheels and tires (I have an intake now) but the difference in acceleration was not even remotely noticeable under any driving conditions. With a heavy wheel it probably would have been. (I have MF-10s which are lighter than stock; in fact, my current wheel and tyre combination is slightly lighter than stock, though rotational inertia may be a little higher.)

Perhaps I lost 0.1 of a second in the 1/4 mile, but the Type-R is slow in the 1/4 mile in any case.


[Modified by norice, 11:31 AM 10/11/2001]

 

I saw an issue of Best Motoring where they compared 2 Miatas. Both current body style but one is newer (more power, 16" rims). The newer one ended up being consistently slower despite of the bigger engine output. Mr. Drift King was pissed and blamed it on the rims and tires. Then they swapped those 16" out and put on the same rims/tires combo as the older one (15"). The newer one won after the swap.

I wouldn't have thought of such a big difference on a track with just a slight increase in overall diameter of the wheels, until I saw that on tape.

 

I am not sure when that article was written, but Mazda revised the claimed horsepower of 2001 Miatas from 155 to 142, so they are not all that more powerful than the 1999/2000s. Sports Compact Car also did a wheel weight versus acceleration test recently. Basically, they discovered that the difference is wheel weight and diameter has to be fairly significant to have an appreciable impact on acceleration.

Going from a 15" to a lighter (or similar weight) 16" on a Type-R is not going to have a significant effect. If the entire focus of your driving is 1/4 mile times, perhaps staying with 15" wheels is advisable, but for me the wider sticker tyres that I have on my 16" wheels outweigh any theoretical acceleration loss.


[Modified by norice, 12:36 PM 10/11/2001]

 

I've been running on the street 215/40/16s. The diameter of this combo is exactly the same as the stock 195/55/15 wheels. Actually, my 16 inch combo is (if I remember correctly) 1 or 2 mm shorter in diameter. This is very insignificant and will not produce the problems outlined in the above posts attributed to running a bigger diameter wheel, since in my case it is not. I would suggest you go with the 16 inch wheels. btw, the Realtime ITRs run on 17x7.5 inch wheels with the Toyo tires.

 

Well since the JDM 16inchers weigh basically around the weight of my stock USDM 15inchers I've notice no difference at all except for better grip through out corning. I use Kumho 712 215/45 16ZR tyres on stock 16inch gunmetel wheels. If you go with 225 wide tyre I would go with sidewall of 40 to kill some of the rubbing at full lock, but the draw back is unless you race hitting hard bumps or pot holes can sometimes transmit so much through the tyre that it actually damages the wheel even cracking it. I saw this about 4 months ago on friends GSR with this setup..though another friend hit the same bump at about the same speed but the thicker side wall tyre absorbed the impact alot better then the lesser one. If you using the 15inchers use 205/50 15 size tyre as for what it's worth best all around if your keeping your 15inchers on.

For dragging I notice alot stang owners use 13-14-15inch wheels normally to reduce the rolling mass..so if your drag race reduce the rolling mass and use wider and sticker tyres up front. I believe the TopFuel CRX uses 14-13inch drag slicks up front.

 

Not quite...
215/40-16 = 57.84cm
195/55-15 = 59.55cm
215/45-16 = 59.99cm

As you can see, the 215/40-16 is close to 20 mm shorter, not 2. The 215/45-16 is quite close to stock diameter...only 4.4mm off.

 

You might want to look around at what tires are available in that size. The reduced availability of tires might make you reconsider going to a bigger wheel. At worst, it won't hurt to check it out first... Just something to consider.