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New wheels & old suspension

6K views 7 replies 6 participants last post by  Fediej 
#1 ·
I'm recommended
(front)17x8 +40 with 215/40 tires and
(rear) 17x9 +40 with 235/40 tires

It's going to be my first time to change anything at all for my crz. Can anyone please inform me if anything else I should know before I do the changes.

I want to stay on the stock suspension to maintain a low budget plan for this summer but will the 17" help look mean and lean enough?? I feel like 18" will throw off my speedo though. Please help:wavey:
 
#2 ·
What are your goals, what do you want out of changing the wheels and tires? If appearance/cosmetic-aesthetics is your goal then those may suit your needs perfectly.

If performance is the goal then you've been recommended sizing based solely on subjective aesthetics. If low budget then I'd consider many other options (starting with non-staggered wheel and tire widths).

18" won't throw off the speedometer unless a bad tire size is chosen, but that large a wheel will likely hurt MPG and overall performance. Speedometer accuracy is dependent on the overall tire diameter.
 
#3 ·
there are many drawbacks to running stagger on a normal daily car.
wider tire = unnecessary drag (esp on a car which won't really benefit from a wider rear tire 90% of the time)
difficult tire rotations... you can "flip" tires for more even wear if your tires are non-directional and don't have an inner/outer orientation, but not front to rear
difficulty matching tire diameters front and rear... on some cars this may pose an issue with abs and other sensors which monitor wheel speed.

if you run 17x8 215 all around, you will maintain proper diameters front and rear while filling in the fenders for a uniform look. you will also be able to rotate your wheels/tires as needed like stock.

unless you have the need for a stagger set up, i would simply place a 10-20mm spacer in the rear (bolt on like H&R if your budget allows), and call it a day. going extra wide on a stock height car looks quite goofy IMO, but to each their own.

as koala stated, speed difference depends solely on tire diameter alone. there are tire size calculators online which can help you determine the required sidewall height for the width you want to run.

also, a 18x8.5 +30 with 225/40 rubs on the rear bumper lip/bolt (where they join). 17x9 +40 with 235/40 may rub depending on tire choice.
 
#4 ·
Don't be scared of large wheel sizes, as long as there not a solid heavy design the negatives are greatly exaggerated. Unless your pushing for the last 1/100th of a second on a track then fit what size you think looks right and works. I'm running 19's with 215/35s lowered on rsr's, no rubbing at all, sharp and precise handling. Putting the 16's back on makes it feel like a sponge....
 
#5 ·
As you go larger in diameter wheel (plus sizing) they're pretty much always heavier than smaller diameter wheel and tire combinations. Even if you get high quality lightweight forged wheels thereby keeping the same wheel weight or lighter (~$500+ a wheel Volk Racing for example) the larger tires are still heavier than equivalent smaller diameters.

For example a random tire chosen on Tire Rack same exact tire for each size listed (no 225 in 15" to compare):
205/50R15 19 lbs.
225/50R16 22 lbs.
225/40R18 23 lbs.
225/35R19 24 lbs.

See how they get heavier despite the reduction in sidewall height. That is maintaining the same width, increasing width results in additional weight as well.

Multiply by four for all four corners, then multiply by whatever figure you deem acceptable for calculating the rotating (unsprung) mass into equivalent sprung mass. Some figures say 2x, while others including some prominent performance automobile manufacturers use a figure as high as 7x.

And:
http://www.crzforum.com/forum/wheels-tires-discussion/69225-lightweight-wheel-test.html

And:
"In general, larger wheels are heavier, and additional weight hinders performance... What’s immediately apparent from the results is that as the wheel-and-tire packages get larger and heavier, acceleration and fuel economy suffer. Neither is a huge surprise, but we measured a 10-percent drop in fuel economy and a four-percent degradation in 0-to-60-mph acceleration from the 15s to the 19s, which is worth considering should you be thinking about “going big.”"
Effects of Upsized Wheels and Tires Tested - Tech Dept. - Car and Driver

Do what you like but the negative effects are not exaggerated. If you like huge wheels then by all means go for it. Many on here report MPG drops after going big and are surprised by it, so its better to give someone correct information than to simply state its exaggerated.

http://www.crzforum.com/forum/honda-cr-z-mpg/39786-mpg-18in-wheels.html
http://www.crzforum.com/forum/wheels-tires-discussion/5740-new-wheels-tires-mpg-weird.html
And more.
 
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