So you're interested in the Additional Rules. Awesome. This guide is an attempt to cover almost everything you need to know about the Additional Rules -- what they are, what they do, and how to get around them.

Before we start though, this is just my personal opinion: If you're trying to beat Tokyo Xtreme Racer for the first time, I highly recommend not enabling the additional rules because they are a massive pain in the ass. The CP gain isn't really worth it unless you're going to be farming at a PA anyway (e.g. Impatient Princess). Committing to maxing out the Battle Reward UP and Win Streak Bonus UP perks first will ensure you'll never be running out of CP so long as you hold onto your win streak.

As for the realism aspect, it's not really that realistic... Engines don't overheat that fast, ECUs aren't nearly that sensitive in real life (unless your tech programmed it that way), and tires don't wear out nearly as fast in real life as they do in-game. There's no achievement associated with enabling the additional rules either.

That said, if you know what you're doing or want to play around with these rules anyway, feel free to play how you'd like. Everyone is entitled to their own way of enjoying the game, and your preference is no more or less valid than someone else's. The additional rule set does make for a more challenging experience, however artificially it may accomplish it.

Please note that some of this information may be incorrect and my observations aren't perfect! If you came to different conclusions than I have or have additional information you think would be useful, please leave a comment and I'll try to get around to it.

As it says in-game, enabling the additional rules artificially increases the game's difficulty by doing a few things:

• The oil and water temperatures of your car's engine will fluctuate and there will be two new gauges on your cluster to monitor them.
  
• Tires will degrade outside of races.
  
• CP gain is increased by 50% on winning battles.

Let's talk about the engine stuff first.

• Your engine essentially has two stamina bars; one for water and one for oil.
  
• There are two conditions on which your temps will rise. 1st is being on the throttle at RPMs ≥ 70% to redline. 2nd is being on the throttle while your turbo's boost pressure is ≥ 50% of maximum boost. These conditions stack on top of each other.
  
• Once your water temp hits 100° C and the gauge light starts flashing, your oil temp will start to go up.
  
• Once your oil temp reads 115° C, your car's ECU kicks in to put your engine in "limp" mode. This mode reduces your rev limit to 70% of your RPM range (effectively locking you out of your power band) and reduces your turbo's maximum boost pressure by half.
  
• Once both your gauges are back to normal (water 90° C, oil 100° C) whether by continuing to limp or by visiting a parking area, "limp" mode is disabled and the engine can run normally again.
  
• On entering the expressway or leaving a parking area, the game will give you a grace period of roughly 30 seconds during which your engine will not overheat at all. Note that this only applies to the engine, not the tires.

The engine won't heat up under all conditions, however. Just full throttling isn't enough to heat up the engine; resistance is a factor as well. Your engine will not heat up in these conditions:

• Revving the engine in neutral or while clutched in via clutch pedal or handbrake.
  
• Bouncing off the rev limiter at speeds well below your top speed, such as 1st to 2nd gear.
  
• Ironically, money shifting (shooting past redline by downshifting at a high engine RPM). It will not overheat the engine at all as the rev limiter prevents you from inputting any throttle.

Feel free to skip this section if you're not interested; these are just my speculations from testing off the Shinonome Bayshore Westbound on-ramp. May or may not be true, someone could test further if they'd like. You may see my notes section further below as well.

• Temps increase at the same rate regardless of how deep into your RPM range you are, i.e. full throttle will overheat the engine the same rate whether at 75% of your RPM range or at 90% of your RPM range. The S4 STI seems to be a strange exception to this, or the factor that disproves this theory, as it has a sizable turbo but also stays towards the end of the tachometer a lot longer.
  
• The same may apply to turbo boost pressure as well; as long as boost pressure is past 50%, temp goes up, though the rate of overheat may scale linearly to the turbo's max boost pressure.

As for the tires, not much to elaborate on; tires will degrade at the same rate outside of races as they do in races.

What you can do to prevent engine overheat:

• Get used to cruising below 70% of your RPM range when not in battle or setting a speed trap or segment record. Do not full throttle even if you're below 70% RPM range, as spooling up your turbo past 50% will heat up your engine as well. 75% throttle pressure or so should be fine.
  
• If your water temp light starts flashing, ease off the throttle. Water cools faster than oil, so you'll want to keep water low.
  
• Use auto-pilot (D-down on controller). You'll stay locked to 60 km/h, but this is an opportunity to go do something else while you wait for your engine to cool if you don't want to modulate your throttle for however long it takes to cool down.
  
• Stay around course loops that have a PA nearby, as parking areas cool your engine immediately. C1 has Hakozaki PA, New Circular Route Clockwise shares Hakozaki and Shibaura PA, and New Circular Route Counterclockwise shares Hakozaki and Tatsumi PA.
  
• Run your last gear or two taller, as taller overdrives[en.wikipedia.org] let you cruise at a higher speed. All cars by default have a reasonably tall overdrive as their last gear, but you may run it taller if you prefer. Cars with 8 gears or more will generally have less of a problem running very tall overdrives as their gearing is closer on average.
  
• Turbocharged engines will overheat faster than naturally aspirated engines. Turbos with higher boost may heat faster as well although this isn't always consistent (e.g. S4 STI may overheat faster than the FL5). Consider cars with naturally aspirated engines (NSX NA2, Lexus cars). These larger displacement engines are heavier and may have worse upgrades, so do keep that in mind.

To avoid tire degradation:

• Aggressive driving such as sliding, drifting, high-speed cornering and braking hard will wear out tires faster. Consider cars with higher in-game lateral grip modifiers. You can look at the car data resources below.
  
• Run a softer brake balance on the tires that wear out faster. This will affect your braking performance, but will wear tires out more evenly.
  
• Run zero toe. Any amount of toe in your wheels will constantly scrub your tires against the road surface as you drive straight, and you spend a lot more time going straight than you do in corners.
  
• Run a milder camber angle. The effect of camber on tire wear is fairly mild, but something to know nonetheless.
  
• Run harder tire compounds. They offer less grip, but degrade slower.

A short example list of cars to consider or avoid depending on certain characteristics. This list is not conclusive; do refer to the car data resources below.

Cars with big turbo engines tend to overheat faster than cars with naturally aspirated engines. These cars, while fast, may not last long between races without cooling down.


These cars have either a naturally aspirated engine or an engine that has a petit turbo. Even after PU upgrades that add a turbo (Lv5+), these engines will not overheat as quickly.

This section isn't essential; just my personal notes on tests with the additional rules.

Main method of testing was starting at Shinonome Bayshore Westbound on-ramp and accelerating to terminal velocity, recording via stopwatch the time it took to hit 100° C water temp with the final RPM. This is more or less "dirty" as it's hard to do consistent pulls to max RPM without variance. Max upgrades (8/5/5...), no legendary tune or nitro. Auto-piloted for 30s before launching to avoid grace period.

Did every run twice to thrice to ensure results stayed mostly consistent.

TTO = Time to Overheat (reach 100° C water temp)

TOKYO XTREME RACER (2025) INFO & DATA RESOURCE[ddm999.github.io]

Feel free to check out other guides as well:
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=3521980913

Guide icon used: https://commons.wikimedia.org/wiki/File:Engine_coolant_temperature.png