HavocRocker

My cousin is trying to tell me that his 17 inch rims make his car top out at 12mph faster then before.

Is this true?

badlx87

Depends on his wheel/tire height and width. If he goes from a low pro 15 to a low pro 17 then yea his car will go faster cuz it'll turn less rpm at set mph. It changes up the gearing kinda.

Jazzer The Cat

No.... his car will not be faster

mrtstang

Depends on what he changed from.

cliffyk

Top speed for any vehicle is determined by one of two factors, engine redline/rev-limiter or horsepower.

If your cousin's car hits redline before running out of HP then it will be faster (top speed) with the larger wheels, OTH if it runs out of horsepower at top speed before hitting redline it will be slower. Either way it will accelerate more slowly with the larger wheels.

For example, our GTs are horsepower limited--if they were not top speed with the stock 3.27 gears would be 225 MPH or so. However my 235 rwHP supercharged 1992 Miata ran out of RPMs (hit redline) at 128.3 MPH, with plenty of HP left...

TOMMY01GT

If his tire circumference was increased, then yes, he will have more top speed.

Lets say his redline is 6500 rpms, and with tires turning their max speed, they would cover, lets say 50" per revolution. with taller tires, he might cover 55" per revolution..with the axels, wheels, and tires turning the exact same RPM @ redline.

changolocs85

quick question...was his top speed actually monitored on some sort of radar device, or is he solely going off his speedo, cuz i thought if you go over 26in of overall tire height your speedo will be off, could this be the issue?

HavocRocker

He said he monitored it on a GPS. But I still highly doubt it raised it 12MPH like he says.

If this is so true then why don't I hear about people putting taller tires on cars?

cliffyk

What size were to original tires, what size are the new ones?

TRUEBLUE3934

Unless he has significantly shorter gears than stock, I doubt switching to taller tires really allowed him to achieve 12 more mph.

Either way, where did he allegedly measure his top speed, and who cares if they can run 140mph vs. 128mph? Taller and heavier wheels/tires will increase his stopping distance, so that is a bad way to go faster.