tire size numbers question

[shinola]

OP i see you have already purchased your tires and i hope they work out well for ya. Just for future reference anyone this link is a great tire size calculator.

http://www.tacomaworld.com/forum/tirecalc.php

[Meathelmet]

Nah, in fact they're not allowed to show a lower speed than actual.

"...The European regulation, ECE-R 39, is more concise, stating essentially that the speed indicated must never be lower than the true speed or higher by more than one-tenth of true speed plus four kilometers per hour (79.5 mph at a true 70). Never low." (Car and Driver is the source).

Hmm, might be the legislation but all the german cars that I have driven in europe disagree with Car and Driver.

All, I mean ALL the VAG concern cars (seat,audi,skoda,vw) read constant 7-9km/hr under. All the volvos,saabs,opels,citroens,alfas & renaults (especially) read under the 5-10km/h or 10%.
Rental cars, test cars, owned,whatever. This is just a personal observation from this side of the pond (running with gps or gps´ses), running with the normal trafic, driving into a police radar, mag tests etc...
This obviously if the car has the normal tyres that you have stated in the registration licence.


Atm I have in my van tyres that are about 5 cm larger in diametre (vw transporter) and with them the gps is about spot on. The tyre calculators show something like 7% speed increase with their calculators.
Wich is a bit bitchy because when you are driving at the "limit", even a slight relapse in concentration can get you a ticket. I have gotten two "you did 83-85 in 80 zone" notices from the police from their
speed cameras in the last year. Just because I adjusted the radio or dug my nose... BLINK...WTF???


Edit : Oh, absolutely no probs with drivetrain on the 4 previous 4wd cars. Everything should be nice and dandy if all the tyres are of the same size. What seems to fuck up the cars is if you raise/lower the ride
height as the cv angle changes..

[legallyillegal]

math made easy

[karpiel]

Are you driving mostly older cars with plastic drive/driven gears/cables/mechanical speedo's or newer cars that use electronic transducers/electronic speedo's etc?

New car standards and o.e. equipment are damn accurate. I've done a lot of gear swaps in new (computer controlled speedo) as well as changing tire size and very rarely is the speedo not accurate afterwards. The ecm can be recalibrated to the gear change and every tire manufacturer has specs for rpm's traveled in a mile allowing for recall as well. Now the mechanically driven stuff is a different story. Especially using aftermarket rear end gears and ratios not offered by the o.e. manufacturer. For example, if I installed a 3.73 or a 4.10 rear end gear, the calibration gear for the trans would have the same number of teeth!

Everything from a Gallardo to a Pinto. By off, I mean marginally, and I credit it to the tires.

Did a quick google and this came up, interesting (to me) read.
http://www.caranddriver.com/features...ometer-scandal

Just put slightly oversized (taller, but skinnier with higher load rating) snows on the ML320 and now the speedo is as dead on as it gets.

[Blurred]

math made easy

People keep posting these, but none have the tires I've got.

I took my stock dodge 2006 ram 2500, and put 37" tires and rims on it.

The speedo change isn't linear, but when I'm doing 70 the speedo reads about 55 mph. heh

[nick > jesus]

The tires on that russian amphibious vehicle actually have enough cubic inches of air to float the vehicle, and the underpan is sealed and the doors, when closed, self-seal against the water. I don't know what the propulsion source is for water travel...might just be the lugs on the tires themselves, but I don't know if that would do it. There's a bunch of videos about the Aton-Impulse Viking on Youtube. It's a pretty rad ride...albeit THIRSTY, I'm sure.

these things look like a blast, i want one

[iceman]

That's cool and all but check out thee Icelandic madmen.