Bigger tires
 

I've been lurking for about 2 months. Read all the FAQs.
93 DelSolSi (D16z6)auto. Running 9 lbs of boost. Engine is being rebuilt right now.

Next upgrade will be to Tein adjustable shock/coil system.

My question is going from the stock 15" rims to 17". What will the offset be for the speedometer ? In other words, when the speedometer says 60 mph, approx. what will my real speed be ?

Re:Bigger tires
 

depends on what size your rubber is ;D ie. if you run 205/40 r17 according to mine and the state patrol it about 5 over..drop down to a 35 series tire and it might be closer to the same http://members.cox.net/corvettejake/...ns/0hammer.gif

Re:Bigger tires
 

You have it backwards... The bigger the outer diameter of your tires are the slower your speedometer will say you are going.

Once you get your new tires just have somebody drive next to you doing the speed limit and they can tell ya how fast you were really going.

Re:Bigger tires
 

go here, everything you are looking for..

http://www.miata.net/garage/tirecalc.html

your welcome...

Re:Bigger tires
 

Thanks for the info.

Re:Bigger tires
 

one thing to remember though too..... even stock tires can change outer diameter by up to a 1/2 inch (or more depending on tread depth) as they wear down. so if you get it close to stock, it's going to be just fine.

Re:Bigger tires
 

ya.. just use the plus sizing system

stock (CRX) = 185/60R14
plus 1 = 195/50R15
plus 2 = 205/40R16

Re:Bigger tires
 

hhhm... can you cram a 205 on a 6.5" rim? 205mm is about 8 inches, that's about 3/4 over the rim. i'm looking at getting a set of 15x6.5 and wanted to get a set of 205/50's. i'm just not up to snuff on my tire sizing....

Re:Bigger tires
 

do 195's on 15" 205 is too wide. if you put 205/50 on 15" you will get a larger rolling diameter and do two things. 1. speedo will be off. 2. gearing will be slightly taller.

Re:Bigger tires
 

actually, stock CRX wheels are 185/60-14. and i was looking at 205/50-15. the link above lists the difference as less than 1/2 diameter and onlt 1.5% speedometer difference (speedo at 60, i'll be traveling 60.9). with autocrossing a lot, i want to get as much rubber down as i can, that's why i was looking at 205.